Stricter TS config

[vincent-psarga]

Summary

The current TS config does not raise any error when a function is declared as returning a specific type but still returns null or undefined.

This may lead to misunderstanding of the functions when relying on the signature.

Expected Behavior

Considering the following code

function doThings(): boolean {
  if (someSpecificCondition) { return null }

  // some more code here
  return true
}

Get a linter error when running make as

Current Behavior

The previous example may compile without any warning.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in a week if no further activity occurs.

[aslakhellesoy]

Lat’s give this priority - ilhaving stricter type checking might reduce bugs.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in a week if no further activity occurs.

[aslakhellesoy]

Reevant article: https://www.figma.com/blog/inside-figma-a-case-study-on-strict-null-checks/

[luke-hill]

@davidjgoss should this be closed and relevant issue(s), raised on the constituent repos if needed?