fix: invalid rd instant availibility call if no infohashes should be checked (#843)

Author: davidemarcoli

src/program/services/downloaders/realdebrid.py

@@ -130,6 +130,9 @@ def get_instant_availability(self, infohashes: List[str]) -> Dict[str, list]:
         Required by DownloaderBase
         """
 
+        if len(infohashes) == 0:
+            return {}
+
         for attempt in range(self.MAX_RETRIES):
             try:
                 response = self.api._request(