fix: do not try to send buffer data if it is empty

In fim, there can be times where no content is arriving, the
buffer is empty. Do not try to guess the start position or send
any content if buffer has not any value

Closes: #373

Author: yrobla

src/codegate/providers/copilot/provider.py

@@ -180,7 +180,7 @@ async def _request_to_target(self, headers: list[str], body: bytes):
         logger.debug("=" * 40)
 
         for i in range(0, len(body), CHUNK_SIZE):
-            chunk = body[i : i + CHUNK_SIZE]
+            chunk = body[i: i + CHUNK_SIZE]
             self.target_transport.write(chunk)
 
     def connection_made(self, transport: asyncio.Transport) -> None:
@@ -343,9 +343,13 @@ async def handle_http_request(self) -> None:
                 new_headers.append(f"Host: {self.target_host}")
 
             if self.target_transport:
-                body_start = self.buffer.index(b"\r\n\r\n") + 4
-                body = self.buffer[body_start:]
-                await self._request_to_target(new_headers, body)
+                if self.buffer:
+                    body_start = self.buffer.index(b"\r\n\r\n") + 4
+                    body = self.buffer[body_start:]
+                    await self._request_to_target(new_headers, body)
+                else:
+                    # just skip it
+                    logger.info("No buffer content arrived, skipping")
             else:
                 logger.error("Target transport not available")
                 self.send_error_response(502, b"Failed to establish target connection")