Add error handling for index file loading in SearchIndex (#948)

Co-authored-by: James Braza <jamesbraza@gmail.com>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: 3 people

paperqa/agents/search.py

@@ -258,9 +258,15 @@ async def index_files(self) -> dict[str, str]:
             if await file_index_path.exists():
                 async with await anyio.open_file(file_index_path, "rb") as f:
                     content = await f.read()
-                    self._index_files = pickle.loads(  # noqa: S301
-                        zlib.decompress(content)
-                    )
+                    try:
+                        self._index_files = pickle.loads(  # noqa: S301
+                            zlib.decompress(content)
+                        )
+                    except Exception:
+                        logger.exception(
+                            f"Failed to load index file {file_index_path}."
+                        )
+                        raise
         return self._index_files
 
     @staticmethod