While editing Java sources in a maven-based multi-module NetBeans Platform application on NetBeans 9.0 beta, the following IDE exception happens at irregular intervals, while editing unrelated files in a different module:
See the attached text file for the complete log dump and stack trace (can't attach the ".dump" file as it contains source code). The source file in question, FilterPanel.java, is generated in part by the Matisse GUI builder (so there's also a FilterPanel.form file). I've also got maven Compile-on-Save enabled.
At other times, occasionally when running the same NetBeans Platform-based application, the application itself throws the following exception, mentioning the same file:
See again the attached text file for the complete log dump and stack trace.