feat: print unexpected error traceback in debug logs

[JamesGuthrie]

When debugging #334 the first thing I needed was a backtrace of the reported error. I added this code to print the backtrace to the debug logs. The resulting log looks as follows:

2025-01-06 14:51:23 [error    ] unexpected error: expected string or bytes-like object
2025-01-06 14:51:23 [debug    ] Traceback (most recent call last):
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/cli.py", line 319, in vectorizer_worker
2025-01-06 14:51:23 [debug    ]     run_vectorizer(
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/cli.py", line 153, in run_vectorizer
2025-01-06 14:51:23 [debug    ]     results = event_loop.run_until_complete(
2025-01-06 14:51:23 [debug    ]   File "/nix/store/53syhg1by396dm23a1in31xqfb62yz0d-python3-3.10.15/lib/python3.10/asyncio/base_events.py", line 649, in run_until_complete
2025-01-06 14:51:23 [debug    ]     return future.result()
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/cli.py", line 148, in run_workers
2025-01-06 14:51:23 [debug    ]     return await asyncio.gather(*tasks)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/vectorizer.py", line 470, in run
2025-01-06 14:51:23 [debug    ]     items_processed = await self._do_batch(conn)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/.devenv/state/venv/lib/python3.10/site-packages/ddtrace/internal/compat.py", line 178, in func_wrapper
2025-01-06 14:51:23 [debug    ]     result = await coro(*args, **kwargs)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/vectorizer.py", line 550, in _do_batch
2025-01-06 14:51:23 [debug    ]     raise e
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/vectorizer.py", line 511, in _do_batch
2025-01-06 14:51:23 [debug    ]     num_chunks = await self._embed_and_write(conn, items)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/.devenv/state/venv/lib/python3.10/site-packages/ddtrace/internal/compat.py", line 178, in func_wrapper
2025-01-06 14:51:23 [debug    ]     result = await coro(*args, **kwargs)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/vectorizer.py", line 619, in _embed_and_write
2025-01-06 14:51:23 [debug    ]     records, errors = await self._generate_embeddings(items)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/vectorizer.py", line 711, in _generate_embeddings
2025-01-06 14:51:23 [debug    ]     chunks = self.vectorizer.config.chunking.into_chunks(item)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/pgai/vectorizer/chunking.py", line 131, in into_chunks
2025-01-06 14:51:23 [debug    ]     return self._chunker.split_text(text)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/.devenv/state/venv/lib/python3.10/site-packages/langchain_text_splitters/character.py", line 118, in split_text
2025-01-06 14:51:23 [debug    ]     return self._split_text(text, self._separators)
2025-01-06 14:51:23 [debug    ]   File "/home/james/workspace/pgai/projects/pgai/.devenv/state/venv/lib/python3.10/site-packages/langchain_text_splitters/character.py", line 88, in _split_text
2025-01-06 14:51:23 [debug    ]     if re.search(_separator, text):
2025-01-06 14:51:23 [debug    ]   File "/nix/store/53syhg1by396dm23a1in31xqfb62yz0d-python3-3.10.15/lib/python3.10/re.py", line 200, in search
2025-01-06 14:51:23 [debug    ]     return _compile(pattern, flags).search(string)
2025-01-06 14:51:23 [debug    ] TypeError: expected string or bytes-like object