only add to cache if not empty

backend/stream_providers.py

@@ -78,6 +78,11 @@ class StreamData():
         return self.values.get("description")
     def complete(self):
         return None not in self.values.values()
+    def has_data(self):
+        for elem in self.values.values():
+            if isinstance(elem, str):
+                return True
+        return False
     def meta(self):
         data = []
         if isinstance(self.values.get("thumbnail"), str):
@@ -246,8 +251,9 @@ async def get_from_runner(cache_key, runner, logger):
     except Exception as e:
         logger.info(e)
     else:
-        upstream_cache[cache_key] = result_temp
-        result = result_temp
+        if isinstance(result_temp, StreamData) and result_temp.has_data():
+            upstream_cache[cache_key] = result_temp
+            result = result_temp
     return result
 
 async def get_streamlink(upstream, proxy, logger):