fix(client): return empty bundles on 404 instead of crashing

[vidiecan]

Problem

A bitstream export walks every item in the cached dspace.all.json and asks DSpace for each item's bundles. An item deleted from the repository since the cache was built answers 404; fetch_resource then returns None, and get_bundles subscripted that None:

'NoneType' object is not subscriptable

— a scary CRITICAL line for what is really just "this item is gone".

Fix

• fetch_resource now records the failing response on self._last_err before dropping the body, so callers can distinguish a gone resource (404) from a transient 5xx.
• get_bundles treats a 404 as a clean empty result (a deleted item simply has no bundles) and returns [].
• Any other failure still falls through and surfaces to the caller, so a transient 5xx keeps its retry and is counted as a failure rather than silently recorded as an item with no files.

9 lines, one file (dspace_rest_client/client.py). _last_err is already initialised to None in __init__, so the getattr(...) guard is safe.

Tests

Covered by tests/test_get_bundles_missing_item.py in the consumer repo (DSpace-ISstag-integration):

• 404 → get_bundles returns [] (no crash)
• 503 → still surfaces (caller retries / counts the failure)

Both pass.

🤖 Generated with Claude Code