Fix ltrim and trim on numeric string

[VincentLanglet]

Closes phpstan/phpstan#13784

[staabm]

nice catch.

[VincentLanglet]

nice catch.

Wasn't easy to understand the issue cause dumpType was displaying numeric-string which is the same than the intersection string&numeric-string.

I dunno if some logic exception should be thrown in some case
For instance an UnionType with an AccessoryType inside ?
Or a call to TypeCombinator::UnionType which returns an AccessoryType ?

[staabm]

I dunno if some logic exception should be thrown in some case
For instance an UnionType with an AccessoryType inside ?
Or a call to TypeCombinator::UnionType which returns an AccessoryType ?

I remember a discussion with ondrey, that we can add a sanity check into TypeCombinator when we can afford a BC break