BUG: Raise TypeError when joining with non-DataFrame using 'on=' (GH#61434)

[iabhi4]

Closes GH#61434

What does this PR change?

When using DataFrame.join() with the on parameter, passing an invalid object like a dict, int, or third-party DataFrame previously resulted in unclear internal errors.

This PR adds a minimal type check that raises a clear TypeError when other is not a DataFrame, Series, or a list of such objects. Valid list-based joins without on remain unaffected.

Checklist

• Closes BUG: Joining Pandas with Polars dataframe produces fuzzy errormessage #61434
• Tests added and passed
• All code checks passed via pre-commit run --all-files
• Entry added in doc/source/whatsnew/v3.0.0.rst

[iabhi4]

All checks passed except the Pyodide build, which failed due to a rate-limit (HTTP 429). The failure seems unrelated to this PR. A rerun should resolve it

[mroeschke]

Suggested change

	if isinstance(other, Iterable) and not isinstance(
	other, (DataFrame, Series, str, bytes, bytearray)
	):
	if is_list_like(other):

[mroeschke]

Also, this probably should be done in merge

[rhshadrach]

@mroeschke - is_list_like will return True on a DataFrame. We only want to enter this block on a potential sequence of DataFrame/Series.

[mroeschke]

Ah OK ignore my suggestion then. But I believe this check should still be done in merge probably

[iabhi4]

Ah OK ignore my suggestion then. But I believe this check should still be done in merge probably

ValueError is raised in join() before the call reaches merge when on is specified. Would you prefer that I let these inputs flow into merge and move the check there for consistency?