Fix Indexable.range_to_index_and_count to not raise IndexError

[straight-shoota]

Fixes #10170

[Sija]

I'd add instead nilable Indexable.range_to_index_and_count?

[straight-shoota]

That'd be more complicated for splatting the tuple.

[asterite]

The problem with this is that now this method is inlined in every other method. Previously it was a different call. Can we maybe make two versions, one with a question mark? And a third one that yields.

[straight-shoota]

Is inlining so bad here?

[asterite]

Indexable.range_to_index_and_count is 20 lines long. It will make those 20 lines appear in every array instance, and that's generic.

I just read @Sija 's suggestion, that's what I'd do to (and it's how it's done everywhere else)

[straight-shoota]

I let Indexable.range_to_index_and_count return nil and used inline return/raise which works pretty fine 👍

[Sija]

@straight-shoota It won't be needed to add all this boilerplate code (raise IndexError.new) if you'd add a nilable method version.

[straight-shoota]

return nil is still necessary, so I'd leave it like that and use a single method for both variants.