vaadin 14.0.0.rc7 webpack error when adding PolymerTemplate

Used the “Create an empty project” vaadin 14 pre-release
Plain Java Servlet.

Run the Maven goal jetty:run
Every thing worked and could view app.

Added a PolymerTemplate class and an PolymerElement (js file) in the frontend/src folder.

and got the follwing errors.


C:\Java\jdk-10.0.2\bin\java.exe -Dmaven.multiModuleProjectDirectory=Q:\DevMaven\vaadin14\applicationform2\applicationform -Xms256m -Xmx512m "-Dmaven.home=C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\plugins\maven\lib\maven3" "-Dclassworlds.conf=C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\plugins\maven\lib\maven3\bin\m2.conf" "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\lib\idea_rt.jar=53075:C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\JetBrains\IntelliJ IDEA 2018.2.1\plugins\maven\lib\maven3\boot\plexus-classworlds-2.5.2.jar" org.codehaus.classworlds.Launcher -Didea.version=2018.2.1 jetty:run -P integration-tests
[INFO]
 Scanning for projects...
[INFO]
                                                                         
[INFO]
 ------------------------------------------------------------------------
[INFO]
 Building applicationform 2.0-SNAPSHOT
[INFO]
 ------------------------------------------------------------------------
[INFO]
 
[INFO]
 >>> jetty-maven-plugin:9.4.15.v20190215:run (default-cli) > test-compile @ applicationform >>>
[INFO]
 
[INFO]
 --- maven-resources-plugin:2.6:resources (default-resources) @ applicationform ---
[INFO]
 Using 'UTF-8' encoding to copy filtered resources.
[INFO]
 Copying 1 resource
[INFO]
 
[INFO]
 --- vaadin-maven-plugin:14.0.0.rc7:prepare-frontend (default) @ applicationform ---
[INFO]
 
[INFO]
 --- maven-compiler-plugin:3.8.0:compile (default-compile) @ applicationform ---
[INFO]
 Nothing to compile - all classes are up to date
[INFO]
 
[INFO]
 --- maven-resources-plugin:2.6:testResources (default-testResources) @ applicationform ---
[INFO]
 Using 'UTF-8' encoding to copy filtered resources.
[INFO]
 skip non existing resourceDirectory Q:\DevMaven\vaadin14\applicationform2\applicationform\src\test\resources
[INFO]
 
[INFO]
 --- maven-compiler-plugin:3.8.0:testCompile (default-testCompile) @ applicationform ---
[INFO]
 Nothing to compile - all classes are up to date
[INFO]
 
[INFO]
 <<< jetty-maven-plugin:9.4.15.v20190215:run (default-cli) < test-compile @ applicationform <<<
[INFO]
 
[INFO]
 --- jetty-maven-plugin:9.4.15.v20190215:run (default-cli) @ applicationform ---
[INFO]
 Logging initialized @6224ms to org.eclipse.jetty.util.log.Slf4jLog
[INFO]
 webAppSourceDirectory not set. Trying src\main\webapp
[INFO]
 Reload Mechanic: automatic
[INFO]
 nonBlocking:false
[INFO]
 Classes = Q:\DevMaven\vaadin14\applicationform2\applicationform\target\classes
[INFO]
 Configuring Jetty for project: applicationform
[INFO]
 Context path = /
[INFO]
 Tmp directory = Q:\DevMaven\vaadin14\applicationform2\applicationform\target\tmp
[INFO]
 Web defaults = org/eclipse/jetty/webapp/webdefault.xml
[INFO]
 Web overrides =  none
[INFO]
 web.xml file = null
[INFO]
 Webapp directory = Q:\DevMaven\vaadin14\applicationform2\applicationform\src\main\webapp
[INFO]
 jetty-9.4.15.v20190215; built: 2019-02-15T16:53:49.381Z; git: eb70b240169fcf1abbd86af36482d1c49826fa0b; jvm 10.0.2+13
Error binding ShutdownMonitor to port 8081: java.net.BindException: Address already in use: NET_Bind
[INFO]
 Scanning elapsed time=302ms
[INFO]
 Initializing AtmosphereFramework
[main]
 INFO com.vaadin.flow.server.startup.DevModeInitializer - Starting dev-mode updaters in Q:\DevMaven\vaadin14\applicationform2\applicationform folder.
[main]
 INFO dev-updater - Scanning classes to find frontend configurations and dependencies...
[main]
 INFO dev-updater - Visited 726 classes. Took 602 ms.
[main]
 INFO dev-updater - Skipping `npm install`.
[main]
 INFO dev-updater - Copying frontend resources from jar files ...
[main]
 INFO dev-updater - Visited 10 jar files. Took 609 ms.
[main]
 INFO dev-updater - Updated Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend\generated-flow-imports.js
[main]
 INFO dev-webpack - Starting webpack-dev-server, port: 53077 dir: Q:\DevMaven\vaadin14\applicationform2\applicationform
   C:\Program Files\nodejs\node.exe Q:\DevMaven\vaadin14\applicationform2\applicationform\node_modules\webpack-dev-server\bin\webpack-dev-server.js --config Q:\DevMaven\vaadin14\applicationform2\applicationform\webpack.config.js --port 53077 -d --inline=false
[webpack]
 INFO dev-webpack - i 「wds」: Project is running at http://localhost:53077/webpack-dev-server/
[webpack]
 INFO dev-webpack - i 「wds」: webpack output is served from /
[webpack]
 INFO dev-webpack - i 「wds」: Content not from webpack is served from Q:\DevMaven\vaadin14\applicationform2\applicationform\target\classes\META-INF\VAADIN, src/main/webapp
[webpack]
 INFO dev-webpack -          Serving the 'stats.json' file dynamically.
[webpack]
 INFO dev-webpack - × 「wdm」: Hash: 475eccb5b93e110ebfe8
[webpack]
 INFO dev-webpack - Version: webpack 4.30.0
[webpack]
 INFO dev-webpack - Time: 1610ms
[webpack]
 INFO dev-webpack - Built at: 08/06/2019 10:47:46 PM
[webpack]
 INFO dev-webpack -                                                                  Asset       Size      Chunks                    Chunk Names
[webpack]
 INFO dev-webpack -                      build/vaadin-bundle-2a130cb83fc0b86090de.cache.js   2.23 MiB      bundle  [emitted]
  [big]
  bundle
[webpack]
 INFO dev-webpack -                  build/vaadin-bundle.es5-65a5125bb7d977170cab.cache.js   2.52 MiB  bundle.es5  [emitted]
  [big]
  bundle.es5
[webpack]
 INFO dev-webpack -                                       build\webcomponentsjs\LICENSE.md   1.52 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                                        build\webcomponentsjs\README.md   10.9 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                      build\webcomponentsjs\bundles\webcomponents-ce.js   16.7 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                  build\webcomponentsjs\bundles\webcomponents-ce.js.map    112 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                build\webcomponentsjs\bundles\webcomponents-sd-ce-pf.js    108 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -            build\webcomponentsjs\bundles\webcomponents-sd-ce-pf.js.map    653 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                   build\webcomponentsjs\bundles\webcomponents-sd-ce.js   80.9 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -               build\webcomponentsjs\bundles\webcomponents-sd-ce.js.map    527 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                      build\webcomponentsjs\bundles\webcomponents-sd.js   65.1 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                  build\webcomponentsjs\bundles\webcomponents-sd.js.map    415 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                   build\webcomponentsjs\custom-elements-es5-adapter.js  924 bytes              [emitted]
         
[webpack]
 INFO dev-webpack - build\webcomponentsjs\entrypoints\custom-elements-es5-adapter-index.js  656 bytes              [emitted]
         
[webpack]
 INFO dev-webpack -        build\webcomponentsjs\entrypoints\webcomponents-bundle-index.js   1.66 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -            build\webcomponentsjs\entrypoints\webcomponents-ce-index.js  672 bytes              [emitted]
         
[webpack]
 INFO dev-webpack -         build\webcomponentsjs\entrypoints\webcomponents-sd-ce-index.js  851 bytes              [emitted]
         
[webpack]
 INFO dev-webpack -      build\webcomponentsjs\entrypoints\webcomponents-sd-ce-pf-index.js   1.19 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -            build\webcomponentsjs\entrypoints\webcomponents-sd-index.js  761 bytes              [emitted]
         
[webpack]
 INFO dev-webpack -                                     build\webcomponentsjs\package.json      3 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                          build\webcomponentsjs\webcomponents-bundle.js    109 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                      build\webcomponentsjs\webcomponents-bundle.js.map    655 KiB              [emitted]
         
[webpack]
 INFO dev-webpack -                          build\webcomponentsjs\webcomponents-loader.js   6.13 KiB              [emitted]
         
[webpack]
 INFO dev-webpack - Entrypoint bundle [big]
 = build/vaadin-bundle-2a130cb83fc0b86090de.cache.js
[webpack]
 INFO dev-webpack - Entrypoint bundle.es5 [big]
 = build/vaadin-bundle.es5-65a5125bb7d977170cab.cache.js
[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/flow-frontend/flow-component-renderer.js]
 7.34 KiB {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/flow-frontend/flow-component-renderer.js]
 5.08 KiB {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-button/theme/lumo/vaadin-button.js]
 72 bytes {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-button/theme/lumo/vaadin-button.js]
 72 bytes {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/color.js]
 7.63 KiB {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/color.js]
 7.43 KiB {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/icons.js]
 87 bytes {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/icons.js]
 87 bytes {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/sizing.js]
 679 bytes {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/sizing.js]
 664 bytes {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/spacing.js]
 1.29 KiB {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/spacing.js]
 1.27 KiB {bundle} [built]

[webpack]
 INFO dev-webpack - [../node_modules/@vaadin/vaadin-lumo-styles/style.js]
 1.24 KiB {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../target/frontend/generated-flow-imports.js]
 1.12 KiB {bundle.es5} [built]

[webpack]
 INFO dev-webpack - [../target/frontend/generated-flow-imports.js]
 1.12 KiB {bundle} [built]

[webpack]
 INFO dev-webpack -     + 207 hidden modules
[webpack]
 INFO dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-form-layout	hemelumoaadin-form-item.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 13:0-67
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-form-layout	hemelumoaadin-form-item.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 13:0-67
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-form-layout	hemelumoaadin-form-layout.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 12:0-69
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-form-layout	hemelumoaadin-form-layout.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 12:0-69
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-select	hemelumoaadin-select.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 14:0-59
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-select	hemelumoaadin-select.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 14:0-59
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-text-field	hemelumoaadin-text-field.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 15:0-67
[webpack]
 ERROR dev-webpack - 
[webpack]
 ERROR dev-webpack - ERROR in ../target/frontend/generated-flow-imports.js
[webpack]
 ERROR dev-webpack - Module not found: Error: Can't resolve '@vaadinaadin-text-field	hemelumoaadin-text-field.js' in 'Q:\DevMaven\vaadin14\applicationform2\applicationform\target\frontend'
[webpack]
 ERROR dev-webpack -  @ ../target/frontend/generated-flow-imports.js 15:0-67
[webpack]
 ERROR dev-webpack - i 「wdm」: Failed to compile.
[webpack]
 ERROR dev-webpack - 
------------------ Frontend compilation failed. -----------------
[INFO]
 DefaultSessionIdManager workerName=node0
[INFO]
 No SessionScavenger set, using defaults
[INFO]
 node0 Scavenging every 600000ms
[main]
 INFO com.vaadin.flow.server.startup.ServletDeployer - Automatically deploying Vaadin servlet with name com.vaadin.flow.server.startup.ServletDeployer to /*
[INFO]
 Started o.e.j.m.p.JettyWebAppContext@2eed6331{/,[file:///Q:/DevMaven/vaadin14/applicationform2/applicationform/src/main/webapp/, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/flow-server/2.0.5/flow-server-2.0.5.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/flow-push/2.0.5/flow-push-2.0.5.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-grid-pro-flow/2.0.1/vaadin-grid-pro-flow-2.0.1.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-combo-box-flow/3.0.2/vaadin-combo-box-flow-3.0.2.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-iron-list-flow/2.0.0/vaadin-iron-list-flow-2.0.0.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-select-flow/2.0.1/vaadin-select-flow-2.0.1.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/flow-data/2.0.5/flow-data-2.0.5.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-date-picker-flow/2.0.2/vaadin-date-picker-flow-2.0.2.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/org/webjars/npm/mobile-drag-drop/2.3.0-rc.1/mobile-drag-drop-2.3.0-rc.1.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/flow-client/2.0.5/flow-client-2.0.5.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-menu-bar-flow/1.0.1/vaadin-menu-bar-flow-1.0.1.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-context-menu-flow/3.0.2/vaadin-context-menu-flow-3.0.2.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-grid-flow/4.0.3/vaadin-grid-flow-4.0.3.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/org/webjars/npm/vaadin__vaadin-mobile-drag-drop/1.0.0/vaadin__vaadin-mobile-drag-drop-1.0.0.jar!/META-INF/resources, jar:file:///C:/Users/andrew/.m2/repository/com/vaadin/vaadin-time-picker-flow/2.0.1/vaadin-time-picker-flow-2.0.1.jar!/META-INF/resources]
,AVAILABLE}{file:///Q:/DevMaven/vaadin14/applicationform2/applicationform/src/main/webapp/}
[INFO]
 Jetty server exiting.
[INFO]
 ------------------------------------------------------------------------
[INFO]
 BUILD FAILURE
[INFO]
 ------------------------------------------------------------------------
[INFO]
 Total time: 12.766 s
[INFO]
 Finished at: 2019-08-06T22:47:47+02:00
[INFO]
 Final Memory: 32M/256M
[INFO]
 ------------------------------------------------------------------------
[ERROR]
 Failed to execute goal org.eclipse.jetty:jetty-maven-plugin:9.4.15.v20190215:run (default-cli) on project applicationform: Failure: Failed to bind to 0.0.0.0/0.0.0.0:9990: Address already in use: bind -> [Help 1]

[ERROR]
 
[ERROR]
 To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR]
 Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
 
[ERROR]
 For more information about the errors and possible solutions, please read the following articles:
[ERROR]
 [Help 1]
 http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[webpack]
 INFO dev-webpack - Stopped 'webpack-dev-server'

Process finished with exit code 1

In the generated-flow-imports.js file found the following

there are backslash and not forward slashes

Not sure if this would cause the problem.

import '@vaadin\vaadin-form-layout\theme\lumo\vaadin-form-layout.js';
import '@vaadin\vaadin-form-layout\theme\lumo\vaadin-form-item.js';
import '@vaadin\vaadin-select\theme\lumo\vaadin-select.js';
import '@vaadin\vaadin-text-field\theme\lumo\vaadin-text-field.js';
const div = document.createElement('div');
div.innerHTML = '<custom-style><style include="lumo-color lumo-typography"></style></custom-style>';
document.head.insertBefore(div.firstElementChild, document.head.firstChild);

import '@vaadin/vaadin-lumo-styles/icons.js';
import '@vaadin/vaadin-lumo-styles/spacing.js';
import '@vaadin/vaadin-lumo-styles/typography.js';
import '@vaadin/vaadin-lumo-styles/style.js';
import '@vaadin/vaadin-lumo-styles/color.js';
import '@vaadin/vaadin-lumo-styles/sizing.js';
import '@vaadin/vaadin-ordered-layout/theme/lumo/vaadin-vertical-layout.js';
import 'Frontend/src/form-address.js';
import '@vaadin\vaadin-form-layout\theme\lumo\vaadin-form-layout.js';
import '@vaadin\vaadin-form-layout\theme\lumo\vaadin-form-item.js';
import '@vaadin\vaadin-select\theme\lumo\vaadin-select.js';
import '@vaadin\vaadin-text-field\theme\lumo\vaadin-text-field.js';
import '@vaadin/vaadin-button/theme/lumo/vaadin-button.js';**
import '@vaadin/flow-frontend/flow-component-renderer.js';
import '@vaadin/vaadin-text-field/theme/lumo/vaadin-text-field.js';
import '@vaadin/vaadin-notification/theme/lumo/vaadin-notification.js';

Thanks for the report. This indeed a very bad regression in RC7 and we’re already fixing it and trying to figure out how it slipped in.