Small protection against fetching results too early

Signed-off-by: Cédric Foellmi <cedric@onekiloparsec.dev>

arcsecond/api/endpoints/_fileuploader.py

@@ -28,12 +28,14 @@ def __init__(self, url, method, data=None, payload=None, **headers):
         self.headers = headers
         self._storage = {}
         self._thread = None
+        self._has_run = False
 
     def start(self):
         if self._thread is None:
             args = (self.url, self.method, self.data, self.payload, self.headers)
             self._thread = threading.Thread(target=self._target, args=args)
         if self._thread.is_alive() is False:
+            self._has_run = True
             self._thread.start()
 
     def _target(self, url, method, data, payload, headers):
@@ -54,7 +56,9 @@ def is_alive(self):
         return self._thread.is_alive()
 
     def get_results(self):
-        response = self._storage.get('response')
+        if self._has_run is False:
+            raise ArcsecondError("Uploader hasn't started. Results can't be retrieved.")
+        response = self._storage.get('response', None)
         if isinstance(response, dict):
             # Responses of standard JSON payload requests are dict
             return response
@@ -64,4 +68,4 @@ def get_results(self):
             else:
                 return None, response.text
         else:
-            return None, self._storage.get('error')
+            return None, self._storage.get('error', None)