Fix non-single functions being parsed for single-only expression infos

[sovdeeth]

Description

Forces the parser to check the plurality of a function before returning it as a valid expression for a given exprInfo.
Also updates the other errors related to plural/single values that weren't being printed and were poorly written.

Before:

Note that the matched pattern only accepts a single number, but since the implementation uses getArray, no issue occurs.
This causes exceptions when used with implementations that use getSingle().

After:

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Target Minecraft Versions: any
Requirements: none
Related Issues: none

[sovdeeth]

Alternative error message. I think it's better but it might be a bit confusing
let me know

[Efnilite]

i think the second one is better if you explain that it's for this specific expression, so e.g.
In this expression, '{a::*}' can only accept a single number, not more.

[sovdeeth]

i prefer the first error message :)

In case it changes your opinion, it has to be changed to this syntax as the parent syntax isn't necessarily an expression

[Efnilite]

i prefer the first error message :)

In case it changes your opinion, it has to be changed to this syntax as the parent syntax isn't necessarily an expression

changed my mind after posting, that's fine to me