Round-1 review on PR #891:
- Guard processor_task's broad except handler against an unbound doc_task
(mirrors multi_user_processor_task): initialise doc_task=None before the loop
and branch the error log. Fixes a latent NameError if receive() raises a
non-TimeoutError/EndOfStream before the first document binds. Regression test
added.
- Drop the unnecessary `from __future__ import annotations` in vector/_errors.py
and express format_exception_group's non-group fast path as an explicit
isinstance check.
- Add a copy_resource Destination-header encoding test (analogue to MOVE);
strengthen the ExceptionGroup test to assert the full leaf repr survives.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
