fix option_if_let_else when Err variant is ignored

[dgulotta]

This fixes an issue where clippy suggests passing a function that takes no arguments as the first argument of Result::map_or_else. The function needs to take one argument. Example that triggers the issue: Playground link

Fixes #10335.

changelog: [option_if_let_else]: fix incorrect suggestion when the contents of an Err variant are ignored

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[samueltardieu]

Thanks for catching this. Since the issue had been closed and not reopened, this apparently flew under the radard.

Can you add a "Fixes #10335" in the PR description and squash your 3 commits into one?

[Manishearth]

issue: this lint says Option, and has Option in its name, we should probably not be linting here?

[Manishearth]

I guess we already lint on Result here.

Tbh I'm not convinced of the value of this lint overall, we should probably have a team discussion about it, but separately to that we shoudl figure out if it should also handle Result in the same lint (and if so, it needs to be updated)