I incorporated the jar into my path, and build passes. But upon starting th

I incorporated the jar into my path, and build passes. But upon starting the application, I get the following:

Failed to find the following imports in the node_modules tree:
- @lrnwebcomponents/pdf-browser-viewer/pdf-browser-viewer.js
If the build fails, check that npm packages are installed.

To fix the build remove package-lock.json and node_modules directory to reset modules.
In addition you may run npm install to fix node_modules tree structure.

2020-07-23 17:00:02.438 INFO 23028 — [ restartedMain]
dev-webpack : Running webpack to compile frontend resources. This may take a moment, please stand by…
2020-07-23 17:00:08.608 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196mERROR in …/target/frontend/generated-flow-imports.jse[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196mModule not found: Error: Can’t resolve ‘@lrnwebcomponents/pdf-browser-viewer/pdf-browser-viewer.js’ in '\target\frontend’e[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196m @ …/target/frontend/generated-flow-imports.js 4:0-68e[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196me[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196mERROR in …/target/frontend/generated-flow-imports.jse[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196mModule not found: Error: Can’t resolve ‘@lrnwebcomponents/pdf-browser-viewer/pdf-browser-viewer.js’ in '\target\frontend’e[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196m @ …/target/frontend/generated-flow-imports.js 4:0-68e[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196mi ?wdm?: Failed to compile.e[0m
2020-07-23 17:00:08.609 ERROR 23028 — [ webpack]
dev-webpack : e[38;5;196m
------------------ Frontend compilation failed. -----------------e[0m

Did you try what the message suggests?