`Unhandled exception` when trying to add redundant file to graph

Start with writerai/resources/graphs.py at GraphsResource.add_file_to_graph and reproduce the request against /v1/graphs/{graph_id}/file using an already-associated file. Trace how the SDK handles the server response and establish the expected behavior for redundant additions; done means the case is handled without an uninformative unhandled exception.

(if you think this is solvable through the SDK alone (pretty sure that is the case), happy to contribute a PR, in that instance any guidance would be awesome)
To reproduce:

from writerai import Writer
from dotenv import load_dotenv
import os

load_dotenv()

WRITER_API_KEY = os.getenv("WRITER_API_KEY")
WRITER_APP_ID = os.getenv("WRITER_APP_ID")
if not WRITER_API_KEY or not WRITER_APP_ID:
    raise ValueError("missing env vars")

client = Writer(api_key=WRITER_API_KEY)

page = client.files.list(graph_id="5f19a...") # Graph containing a file
graph_id = page.data[0].graph_ids[0]
file_id = page.data[0].id

graph_file = client.graphs.add_file_to_graph(
    graph_id=graph_id,
    file_id=file_id
)

Error message:

---------------------------------------------------------------------------
InternalServerError                       Traceback (most recent call last)
Cell In[5], [line 18](vscode-notebook-cell:?execution_count=5&line=18)
     [15](vscode-notebook-cell:?execution_count=5&line=15) graph_id = page.data[0].graph_ids[0]
     [16](vscode-notebook-cell:?execution_count=5&line=16) file_id = page.data[0].id
---> [18](vscode-notebook-cell:?execution_count=5&line=18) graph_file = client.graphs.add_file_to_graph(
     [19](vscode-notebook-cell:?execution_count=5&line=19)     graph_id=graph_id,
     [20](vscode-notebook-cell:?execution_count=5&line=20)     file_id=file_id
     [21](vscode-notebook-cell:?execution_count=5&line=21) )

File c:\Notes\writer\.venv\lib\site-packages\writerai\resources\graphs.py:311, in GraphsResource.add_file_to_graph(self, graph_id, file_id, extra_headers, extra_query, extra_body, timeout)
    [309](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:309) if not graph_id:
    [310](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:310)     raise ValueError(f"Expected a non-empty value for `graph_id` but received {graph_id!r}")
--> [311](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:311) return self._post(
    [312](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:312)     f"/v1/graphs/{graph_id}/file",
    [313](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:313)     body=maybe_transform({"file_id": file_id}, graph_add_file_to_graph_params.GraphAddFileToGraphParams),
    [314](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:314)     options=make_request_options(
    [315](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:315)         extra_headers=extra_headers, extra_query=extra_query, extra_body=extra_body, timeout=timeout
    [316](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:316)     ),
    [317](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:317)     cast_to=File,
    [318](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/resources/graphs.py:318) )

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1275, in SyncAPIClient.post(self, path, cast_to, body, options, files, binary_request, stream, stream_cls)
   [1255](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1255) def post(
   [1256](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1256)     self,
   [1257](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1257)     path: str,
   (...)
   [1265](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1265)     stream_cls: type[_StreamT] | None = None,
   [1266](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1266) ) -> ResponseT | _StreamT:
   [1267](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1267)     opts = FinalRequestOptions.construct(
   [1268](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1268)         method="post",
   [1269](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1269)         url=path,
   (...)
   [1273](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1273)         **options,
   [1274](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1274)     )
-> [1275](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1275)     return cast(ResponseT, self.request(cast_to, opts, stream=stream, stream_cls=stream_cls))

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:958, in SyncAPIClient.request(self, cast_to, options, remaining_retries, stream, stream_cls)
    [955](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:955) else:
    [956](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:956)     retries_taken = 0
--> [958](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:958) return self._request(
    [959](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:959)     cast_to=cast_to,
    [960](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:960)     options=options,
    [961](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:961)     stream=stream,
    [962](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:962)     stream_cls=stream_cls,
    [963](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:963)     retries_taken=retries_taken,
    [964](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:964) )

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1046, in SyncAPIClient._request(self, cast_to, options, retries_taken, stream, stream_cls)
   [1044](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1044) if remaining_retries > 0 and self._should_retry(err.response):
   [1045](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1045)     err.response.close()
-> [1046](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1046)     return self._retry_request(
   [1047](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1047)         input_options,
   [1048](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1048)         cast_to,
   [1049](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1049)         retries_taken=retries_taken,
   [1050](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1050)         response_headers=err.response.headers,
   [1051](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1051)         stream=stream,
   [1052](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1052)         stream_cls=stream_cls,
   [1053](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1053)     )
   [1055](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1055) # If the response is streamed then we need to explicitly read the response
   [1056](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1056) # to completion before attempting to access the response text.
   [1057](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1057) if not err.response.is_closed:

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1095, in SyncAPIClient._retry_request(self, options, cast_to, retries_taken, response_headers, stream, stream_cls)
   [1091](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1091) # In a synchronous context we are blocking the entire thread. Up to the library user to run the client in a
   [1092](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1092) # different thread if necessary.
   [1093](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1093) time.sleep(timeout)
-> [1095](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1095) return self._request(
   [1096](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1096)     options=options,
   [1097](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1097)     cast_to=cast_to,
   [1098](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1098)     retries_taken=retries_taken + 1,
   [1099](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1099)     stream=stream,
   [1100](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1100)     stream_cls=stream_cls,
   [1101](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1101) )

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1046, in SyncAPIClient._request(self, cast_to, options, retries_taken, stream, stream_cls)
   [1044](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1044) if remaining_retries > 0 and self._should_retry(err.response):
   [1045](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1045)     err.response.close()
-> [1046](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1046)     return self._retry_request(
   [1047](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1047)         input_options,
   [1048](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1048)         cast_to,
   [1049](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1049)         retries_taken=retries_taken,
   [1050](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1050)         response_headers=err.response.headers,
   [1051](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1051)         stream=stream,
   [1052](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1052)         stream_cls=stream_cls,
   [1053](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1053)     )
   [1055](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1055) # If the response is streamed then we need to explicitly read the response
   [1056](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1056) # to completion before attempting to access the response text.
   [1057](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1057) if not err.response.is_closed:

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1095, in SyncAPIClient._retry_request(self, options, cast_to, retries_taken, response_headers, stream, stream_cls)
   [1091](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1091) # In a synchronous context we are blocking the entire thread. Up to the library user to run the client in a
   [1092](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1092) # different thread if necessary.
   [1093](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1093) time.sleep(timeout)
-> [1095](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1095) return self._request(
   [1096](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1096)     options=options,
   [1097](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1097)     cast_to=cast_to,
   [1098](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1098)     retries_taken=retries_taken + 1,
   [1099](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1099)     stream=stream,
   [1100](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1100)     stream_cls=stream_cls,
   [1101](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1101) )

File c:\Notes\writer\.venv\lib\site-packages\writerai\_base_client.py:1061, in SyncAPIClient._request(self, cast_to, options, retries_taken, stream, stream_cls)
   [1058](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1058)         err.response.read()
   [1060](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1060)     log.debug("Re-raising status error")
-> [1061](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1061)     raise self._make_status_error_from_response(err.response) from None
   [1063](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1063) return self._process_response(
   [1064](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1064)     cast_to=cast_to,
   [1065](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1065)     options=options,
   (...)
   [1069](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1069)     retries_taken=retries_taken,
   [1070](file:///C:/Notes/writer/.venv/lib/site-packages/writerai/_base_client.py:1070) )

InternalServerError: Error code: 500 - {'tpe': 'fail.internal.generic', 'errors': [{'description': 'Unhandled exception', 'key': 'fail.internal.generic', 'extras': None}], 'extras': None}

(note i was not able to test adding an actual new file because of #155 )