`trimStart` thowing on multi-character string `chars` is a breaking change and a Lodash compatibility break

[foucdeg]

Hello,

Just some feedback about the fix #1615 introduced in v1.49 (trimStart throwing an error when chars is a multi-character string).
While I understand and agree with the intention, transforming an undeterminate behaviour into a thrown error should have been considered a breaking change. It did break something on our side.
IMO, the better way to introduce this in a minor release should have been a deprecation warning.

I also suggest editing the docs to make this constraint more explicit. While the examples only show one-character strings, the spec for the argument does not specify that it should be a one-character string. This is especially important for people migrating from Lodash (as Lodash's equivalent does support multi-character strings - this breaks the 1-1 compatibility promise).

Thanks for the hard work!

[Hprogram]

Some findings that might help triage this:

The compat package is not affected — es-toolkit/compat's trimStart/trimEnd split a string chars into a character array before delegating (chars.toString().split('')), so they keep lodash's "set of characters" semantics and never throw. The existing compat tests cover multi-character strings (e.g. trimStart('-_-abc-_-', '_-')). So the 1-1 lodash compatibility promise still holds for es-toolkit/compat — the throw only affects the main es-toolkit package (introduced in #1615 for trimStart; trimEnd has the same validation, and trim inherits it from both).

The docs were inconsistent about it — trimEnd's reference docs already document the constraint with an #### Errors section in all four languages, but trimStart and trim didn't mention it in any language.

Whether the v1.49 behavior change should have been treated as breaking is of course a maintainer call — but regardless of that outcome, the docs should match the implementation, so I've submitted #1936 adding the missing Errors sections to trimStart/trim across the four languages, mirroring the existing trimEnd wording.

[foucdeg]

Thanks, I didn't know about es-toolkit/compat - makes more sense now.