extract_text_before/extract_text_after raise UnboundLocalError when the pattern is absent

Summary

extract_text_before() and extract_text_after() (in unstructured/cleaners/extract.py) raise an UnboundLocalError instead of a clear error when the given pattern does not occur in the text at all. The helper they call, _get_indexed_match(), tries to build a "not found" message using a loop variable that was never assigned because the loop body never ran.

Reproduction

from unstructured.cleaners.extract import extract_text_before

# "xyz" does not appear in the text, so there are zero matches
extract_text_before("hello world", "xyz")

Actual

UnboundLocalError: cannot access local variable 'i' where it is not associated with a value

Expected

Either the intended ValueError ("Result with index 0 was not found.") or a graceful no-match result. The confusing UnboundLocalError should not surface.

Root cause

In _get_indexed_match:

for i, result in enumerate(re.finditer(pattern, text)):
    if i == index:
        regex_match = result

if regex_match is None:
    raise ValueError(f"Result with index {index} was not found. The largest index was {i}.")

When re.finditer(pattern, text) yields no matches, the for loop never executes, so i is never bound. The regex_match is None branch is then taken and the f-string references {i}, which raises UnboundLocalError before the intended ValueError can be raised. This is the normal "pattern absent" path, so any caller of extract_text_before / extract_text_after with a pattern that is not present hits it.

Suggested fix

Initialize the counter before the loop so the message is well-defined on zero matches, e.g.:

i = -1
for i, result in enumerate(re.finditer(pattern, text)):
    ...
if regex_match is None:
    raise ValueError(
        f"Result with index {index} was not found."
        + (f" The largest index was {i}." if i >= 0 else " No matches were found.")
    )

Happy to send a small PR with a regression test if that helps.

Start in unstructured/cleaners/extract.py and inspect _get_indexed_match(), then run the provided extract_text_before() reproduction with an absent pattern. Add regression coverage for the zero-match path and verify it no longer exposes UnboundLocalError, instead producing the intended ValueError or graceful no-match result.