chore: add to ignore file

[brettz9]

closes #1141

Also:

• chore: tsconfig fixes
• test: demo checking of observer call; #1144
• test: properly report missing errors; use file extension in import

[github-actions[bot]]

:tada: This PR is included in version 46.5.0 :tada:

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• GitHub release
• npm package (@latest dist-tag)

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