Fix #193468 - Fix bug with error notification when pressing "l" on non-expandable reference item.

[audreygao]

Fixes #193468

• Pressing "l" key on expandable reference item expands it. Pressing "l" on non-expandable reference item opens the reference and no longer shows error notification.
• Fixes the same issue with pressing "l" on non-expandable items ini "Go to Implementation" list.

Cause of bug:

• Pressing "l" key on non-expandable reference item triggers selectElement function in listCommand.ts, which calls AbstractTree's setSelection and setAnchor function. AbstractTree's setSelection function will (1) fire the given event, in this case open the selected reference item and dispose the list widget, (2) call the list widget's setSelection function. The list widget is thus empty with a list length of 0 after step (1), leading to error notification in step (2). Swapping step (1) and (2) fixes the issue.
• AbstractTree's 'setAnchor' function also checks on the list widget's length. Calling this function after setSelection also triggers the error notification. Calling setAnchor before setSelection in selectElement function fixes the issue.

Issue fixed on "Go to Reference":

ReferenceListFix.mov

Issue Fixed on "Go to Implementations":

ImplementationsListFix.mov

[audreygao]

@microsoft-github-policy-service agree

[joaomoreno]

Thanks! 🍻