How Disable popup Error Stack in Vaadin Portlet

I am writing portlets with vaadin7. I have to use some classes which are not serializable (and also can not be made). They are working without problems but when I mouseover the button who calles them somewhere, a big popup appears and tells me about some null pointer exception (which seems to be caused by the try to serialize these objects)

How can I disable this error popup? see attachment for screenshot

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