Unhandled exception on isinstance(..., JException)

[pulkin]

Thanks again for the project!

I have some code to wrap exceptions and send them to parent (python) process. For jpype, I had to add this because JException cannot be serialized:

def wrap_into_traceback(e: BaseException, trim: int = 0) -> traceback.TracebackException:
    ...
    if isinstance(e, JException):
        e = RuntimeError(f"{e.message()}\nTraceback:\n{e.stacktrace()}")

This works most of the time except raising from startJVM(jvmpath="does-not-exist"). Trying to reproduce this in a minimal code, I see this error as OSError: [Errno 0] JVM DLL not found but in the production example it segfaults raises unhandled JPypeException on isinstance (fortunately, can see the traceback). Not sure how to debug this.

terminate called after throwing an instance of 'JPypeException'
Fatal Python error: Aborted
...
Current thread 0x00007f42b216a740 (most recent call first):
File "/home/pulkin/.../something.py", line 87 in wrap_into_traceback

[marscher]

I think this is a corner case, when the JVM could not be initialized due to the missing library (or dll) and therefore the JException type is incomplete (the Java side of it cannot be constructed, because the JVM is not running).
You need to ensure the JVM is running, when using JException. Or handle the corner case, that jvm_path does not exist.