[debug] cancellation of attach by PID leaves dangling promises

[AlexTugarev]

While testing #7314 I learned about a dangling promise, which causing a never ending progress. When you try to attach to a running process, but then dismiss the quick open menu with esc, the awaiter will never continue at

theia/packages/debug/src/browser/debug-session-manager.ts

Line 169 in 1ca3ec3

await this.fireWillStartDebugSession();

cc. @akosyakov

[akosyakov]

I think it is caused by #5764 and #5764.

The fix is here in gitlens PR: 9c7d064

I will extract it to a separate PR then.

[akosyakov]

No, it is something else. It looks like debugger can participate in the variable resolution: https://github.com/microsoft/vscode-node-debug/blob/501ceedca3b4e8aa1d0f62780558a0102dc8930a/package.json#L163-L165

So for us variable PickProcess never resolves to extension.pickNodeProcess

Edit: nope it does not seem to be a reason as well, although we are missing it.

[akosyakov]

So it is combination of #7316 (comment) and #7316 (comment) what causing it.