removesuffix helper returns an empty string for an empty suffix #182

Description

The internal removesuffix helper claims to backport str.removesuffix, but it returns an empty string when the requested suffix is empty.

Code reference

src/browserbase/_utils/_utils.py:368-375

The implementation executes string[:-len(suffix)]; for an empty suffix this becomes string[:-0], which is string[:0].

Reproduction

from browserbase._utils._utils import removesuffix

print(repr(removesuffix("abc", "")))
print(repr("abc".removesuffix("")))

Actual:

''
'abc'

Expected behavior

To match the documented stdlib behavior, an empty suffix should leave the original string unchanged.

Why it matters

This shared helper silently corrupts input for a valid edge case and has no direct test coverage. Even though current in-repo call sites are limited, it is exported through browserbase._utils and may be reused by generated or manual code later. The fix is small (if suffix and string.endswith(suffix): ...) and should include empty-string tests for both prefix/suffix helpers.