Improve ollama error messaging (#37)

Author: djcopley

src/shelloracle/providers/ollama.py

@@ -78,6 +78,9 @@ async def generate(self, prompt: str) -> AsyncIterator[str]:
             async with httpx.AsyncClient() as client:
                 async with client.stream("POST", self.endpoint, json=data, timeout=20.0) as stream:
                     async for line in stream.aiter_lines():
-                        yield json.loads(line)["response"]
+                        response = json.loads(line)
+                        if "error" in response:
+                            raise ProviderError(response["error"])
+                        yield response["response"]
         except (httpx.HTTPError, httpx.StreamError) as e:
             raise ProviderError(f"Something went wrong while querying Ollama: {e}") from e