javac errors while editing temporarily incorrect code

[Eirik Bakke <eb...@ultorg.com>]

In NetBeans 11.3 with Java 14, I have noticed many cases of error dialogs popping up while editing source code. Usually the source code is in a temporarily incorrect state--but the editor should be able to handle this gracefully. Some of the errors are assertion errors at the com.sun.tools.javac level. I don't know this part of the IDE codebase very well, so I'm not sure whether these problems are caused by nbjavac (which I do have installed), the Java 14 javac, or in some cases higher-level NetBeans editor highlighting code.

Here are four examples of such errors:
https://issues.apache.org/jira/browse/NETBEANS-4095 (NPE inside javac)
https://issues.apache.org/jira/browse/NETBEANS-4177 (IOOBE at the NetBeans SemanticHighlighterBase level)
https://issues.apache.org/jira/browse/NETBEANS-4179 (AssertionError inside javac/FlowAnalyser)
https://issues.apache.org/jira/browse/NETBEANS-4180 (AssertionError inside javac/Analyzer)

In many cases I expect the user experience could be improved by simply suppressing the errors. Though ideally the editor should be able to skip the syntax errors and parse the correct portions of the file. And NPEs and AssertionErrors inside javac should ideally be fixed there, even when parsing temporarily incorrect source files.

-- Eirik