fix(language-service): Clear caches when program changes

[kyliau]

This commit fixes a bug whereby the empty set of analyzed modules is
cached and subsequently produces the incorrect error 'Component ... is
not included in a module...'

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] angular.io application / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Error message 'Component ... is not included in a module...' is incorrectly shown.

Issue Number: 19405

What is the new behavior?

Language service no longer shows incorrect error message.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[chuckjaz]

This code looks completely unnecessary to me and, if it has an effect, there is something more fundamental that is going wrong.

The only way analyzedModules should change is if the content of the program changes. Since validate will clear analyzedModules whenever that happens (called before calling ensureAnalyzedModules() the only way this change would have the desired effect is there was something wrong with validate().

[ngbot]

I see that you just added the PR action: merge label. It won't do anything good though, because the following checks are still failing:

• missing required label: "PR target:"

If you want your PR to be merged, it has to pass all the checks. But if you have a good reason to want to merge this, please contact the caretaker to let them know.

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