No stack trace or thrower position highlighting on exception

[lammich]

Most appropriate sub-area of Processing 4?

PDE

Processing version

4.4.4

Operating system

Ubuntu 24.04, Windows 10

Bug description

The location of an exception (e.g. NullPointerException) is not highlighted, nor is a stack trace printed. The only information printed is a red NullPointerException message at the bottom. There is no obvious way how to find out where this was thrown.

This seems to be a regression to earlier 3.x versions, where the line of the thrower would be at least highlighted.

Steps to reproduce this

"1. open the below snippet in PDE

2. run the snippet

3. observe that the error message (NullPointerException) is not linked to any position in the code, nor is any position in the code highlighted, nor is a stack-trace or similar printed anywhere"

snippet

PVector [] vs = new PVector[10];
for (int i=0;i<vs.length;++i)
  vs[i].set(0,0);   // <-- this position should be contained in the error message

Additional context

real showstopper when trying to debug any bigger program in PDE!

Would you like to work on the issue?

No, I’m just reporting the issue

[Stefterv]

Hi @lammich Thank you for reporting this issue and giving such detailed context! I just tested it and it seems to be a regression in 4.4.x. It has probably something to do with the integrated JDK within Processing. I suspect that the error reporting probably looking in the wrong place for now.

[Stefterv]

Traced it down to here:

processing4/app/src/processing/app/ui/Editor.java

Line 2556 in 19c8b1e

if (e instanceof SketchException re) {

the code is expecting a processing.app.SketchException and has been given a processing.java.preproc.SketchException missing this if check.

So the origin of the problem is that we had a circular reference to SketchException which was dealt with by copying the class but instead should have been migrated out off the app instead

[joshgiesbrecht]

I'd like to give this a try. Are other modes all going to have their own versions of SketchException that app code is going to need to look at through an adapter-ish class of some kind?
edit: or an interface

[SableRaf]

Hi @joshgiesbrecht and thanks for your interest! I have assigned the issue to you.

cc @Stefterv knows more about our plans for modes.

[Stefterv]

Hi @joshgiesbrecht great that you are interested in taking this one up!

This looks similar to #1104, where we're currently in the process of moving an app class into a standalone app.utils package for reuse. I think the same approach applies here. Extract and extend the class and move it into app.utils so it can be shared more broadly.

The steps should be largely the same as what’s being done in #1104.