Analyze current `path` and log invalid items as soon as extension loads

[DonJayamanne]

See here #342 (comment)

Existence of the ; or ;; characters in the Path variable are known to result in the failure of the extension to load. If the extension fails to load please modify your paths to remove these characters.

Related issues:

• Extension host terminated unexpectedly #342
• https://github.com/DonJayamanne/pythonVSCode/issues/1071

[DonJayamanne]

Brett Cannon (@brettcannon)

• Currently I'm looking for paths that contain ;

• Based on feed back in Extension host terminated unexpectedly #342, that what has caused issues.

• However I will not be checking for the existence of individual paths. I'm on the fence on this, as performing this checks could significantly slow down the load times of the extension.

If this is necessary we could have a flag that if turned on, will perform that check as well.
I.e. if extension fails to load, the user could turn on a setting (something similar to dump all diagnostics messages), causing the extension to be more strict with the checks.

[brettcannon]

Didn't we have another issue where things didn't work if a path entry didn't exist?

[DonJayamanne]

Didn't we have another issue where things didn't work if a path entry didn't exist?

I think yes, Let me check,

[DonJayamanne]

Didn't we have another issue where things didn't work if a path entry didn't exist?

Couldn't find such an issue, proceeding without this check, should be easy to add that if necessary (on Monday). Will look through issues on Monday as well.

[DonJayamanne]

Message displayed:

[brettcannon]

Don Jayamanne (@DonJayamanne) "the Python extension not to load" or "to not load"; missing the "to".