Exception during the ICmpInitializable.OnShutdown event skips all remaining OnShutdowns

[Rick-van-Dam]

Summary

A Exception during the ICmpInitializable.OnShutdown event will skip any ICmpInitializable.OnShutdown after that. Looking at the source code here its easy to see why since there is no try catch to prevent this from happening. This can cause all kinds of weird bugs such as events not being unsubscribed.

A solution would be to collect all exceptions and throw/log them after all Shutdowns have executed.

Consider applying this to all events.

How to reproduce

• Download ShutdownSkipped.zip
• Open and run it in the editor. Note that even though we have 2 components only 1 of them has its shutdown executed

Workaround

• Prevent any Exceptions during this event.

[ilexp]

There are no editor guards in place in order to prevent an exception from inside user code getters or setters to propagate into the editor - however, I think it should be possible to add try / catch clauses like that in spots where these kinds of errors are most likely to occur.

Is there a callstack we can work with? From where exactly is that getter called when the problem occurs?

[Rick-van-Dam]

So I tried the following things:
-Make the property invisible in the UI.
-Change the property to a method.

Neither of those changes seem to solve the problem but it doesnt seem to be caused by the UI (directly, maybe still indirect?. Restarting duality does fix the issue.

The code is used in a DualityApp.Mouse.ButtonDown event. Iam still in the process of isolating this completely so sorry for the current lack of info.

EDIT: here is a test project to easily reproduce this error. Instructions can be found at the top of the issue:
NullreferenceBugInEditorResearch.zip)

[Rick-van-Dam]

Ah seems I have forgotten to unsubscribe the DualityApp.Mouse.ButtonDown event. This in addition to the fact that new GameObjects/Components are created when you enter/leave sandbox mode means you will be calling methods on objects that are supposed to be out of scope. So this was really a (rather stupid :P) bug caused by myself.

Aside from that fact though it would be nice if the editor actually told you forgot to unsubscribe some event.

EDIT: seems that was the case in the test project I uploaded here but not in pathfindax.
EDIT2: seems to be caused by the fact that one of my ICmpInitializable.OnShutdown had a exception in it. This prevented the execution of all ICmpInitializable.OnShutdown after that. Looking at the duality source its easy to see why. There is no try catch around the shutdownlist so it just skips the rest of the list once a exception has occured.
EDIT3: updated the first comment to reflect the above observations. Maybe this issue needs to be splitted in 2 later on.

[ilexp]

Let's refocus this issue towards guarding against forgotten public event subscriptions then 👍

Can you rename / edit the issue to reflect this? Don't remove the old description and repro sample though, doesn't hurt to have them still around, maybe just "quote" them at the bottom as original text.