fix: check HTTP response status before parsing JSON body

upload_image() calls r.json() before checking r.ok. If the server
returns an error response (401, 500, etc) with a non-JSON body,
this raises a confusing JSONDecodeError instead of the intended
'Unable to get signed urls' error message.

Move the r.ok check before the r.json() call.

frigate/plus.py

@@ -105,9 +105,10 @@ class PlusApi:
 
     def upload_image(self, image: ndarray, camera: str) -> str:
         r = self._get("image/signed_urls")
-        presigned_urls = r.json()
+        
         if not r.ok:
             raise Exception("Unable to get signed urls")
+        presigned_urls = r.json()
 
         # resize and submit original
         files = {"file": get_jpg_bytes(image, 1920, 85)}