feat: Adding RequireProp type helper

[fiddur]

Helpful type to require one property in a type. Could be used like

  const changeEntries = dailyEntries.entries.filter(
    (e): e is RequireProp<Entries, 'change'> => !!e.change,
  )

...to allow accessing the entry.change property later without warning about Could be undefined.

[fiddur]

Not sure about naming here. Could be RequiredProp (rather than require...). Or RequiredPick since we are picking one property.

[mrnagydavid]

Not seeing how this would be used, I say LGTM, but in my experience Kirill has opinions on being too precise with types, so I'll defer to him.

If it's an internal, one-off thing somewhere in our helpers ✅
But if other developers can face both versions of DailyEntries - one with optional and one with the required property -, then I'd probably create a new named interface/type. (Of course, we can create a new named interface/type using this helper too, which would be okay too.)

I like the RequiredProp name - from all the other options you mentioned.
I wonder about making it accept more than one key though, e.g. RequiredProps, or WithRequiredProps.

[fiddur]

I was using it in a filter rule and then wanting to use the filtered data without checking again or using the non-null assertion operator !

[fiddur]

Actually right now I don't need it anymore (change of solution), but I have used this previously and find it useful to avoid the !.

[kirillgroshkov]

I don't mind it.
RequiredProp name SGTM.

I also don't mind not shipping it until it's needed.
Both fine by me.