fix(participants) do not preload gravatars if config is empty

Previously gravatars (external resources) were preloaded even if
disableThirdPartyRequests was set to true in the config, as the
config may be empty at the time of preloading.

Closes: #5670
Signed-off-by: Christoph Settgast <csett86@web.de>

react/features/base/participants/middleware.js

     // to the new avatar and emit out change events if necessary.
     const result = next(action);
 
-    const { disableThirdPartyRequests } = getState()['features/base/config'];
-
-    if (!disableThirdPartyRequests && (avatarURL || email || id || name)) {
-        const participantId = !id && local ? getLocalParticipant(getState()).id : id;
-        const updatedParticipant = getParticipantById(getState(), participantId);
-
-        getFirstLoadableAvatarUrl(updatedParticipant, store)
-            .then(url => {
-                dispatch(setLoadableAvatarUrl(participantId, url));
-            });
+    // Only run this if the config is populated, otherwise we preload external resources
+    // even if disableThirdPartyRequests is set to true in config
+    if (Object.keys(getState()['features/base/config']).length) {
+        const { disableThirdPartyRequests } = getState()['features/base/config'];
+
+        if (!disableThirdPartyRequests && (avatarURL || email || id || name)) {
+            const participantId = !id && local ? getLocalParticipant(getState()).id : id;
+            const updatedParticipant = getParticipantById(getState(), participantId);
+
+            getFirstLoadableAvatarUrl(updatedParticipant, store)
+                .then(url => {
+                    dispatch(setLoadableAvatarUrl(participantId, url));
+                });
+        }
     }
 
     // Notify external listeners of potential avatarURL changes.