An error occurs when canceling C# durable project debugging via prompt dialog

[v-ruizh]

OS: Windows 11
Build Version: 20250613.1
.NET Version: 9.0.301
Regression: Not a regression

Repro Steps:

1. Create a .NET 9 Isolated C# durable project.
2. Debug the above project, a dialog pops up. Such as the below one.
   
3. Click "Cancel" or "X" button in the above dialog.
4. Check whether no error occurs.

Expect:
No error occurs.

Actual:
An error occurs.

More Info:
This issue does not reproduce for JavaScript/TypeScript durable project.

[motm32]

Does this still occur ? If so does trying again fix the issue?

[v-ruizh]

Does this still occur ? If so does trying again fix the issue?

Yes, this issue still reproduces on the latest main branch build 20250807.1. Trying again can't fix the issue.

[MicroFish91]

Ahh, this is because the pre-debug validation logic for each connection setting is separate from the main flow; so canceling still allows the rest of the validation to go through...

As long as we allow for a skip option, cancel should probably stop the entire workflow. The best time to address this will probably be when we merge all pre-debug validation logic into one flow. We have a todo to improve activity log support for the pre-debug validation process. We should address this in tandem once we start making those changes.