fix(mobile-pagination): address PR review comments

react/features/filmstrip/components/native/Filmstrip.js

                     renderItem = { this._renderThumbnail }
                     showsHorizontalScrollIndicator = { false }
                     showsVerticalScrollIndicator = { false }
-                    style = { styles.scrollView }
+                    style = { styles.flatListStageView }
                     viewabilityConfig = { this._viewabilityConfig }
                     windowSize = { 2 } />
                 {

react/features/filmstrip/components/native/Thumbnail.js

     _isFakeParticipant: boolean,
 
     /**
-     * Indicates whether the participant is fake.
+     * Indicates whether the participant is screen sharing.
      */
     _isScreenShare: boolean,
 
     }
 
     /**
-     * Implements React's {@link Component#render()}.
+     * Renders the indicators for the thumbnail.
      *
-     * @inheritdoc
      * @returns {ReactElement}
      */
-    render() {
+    _renderIndicators() {
         const {
             _audioMuted: audioMuted,
             _isScreenShare: isScreenShare,
             _renderDominantSpeakerIndicator: renderDominantSpeakerIndicator,
             _renderModeratorIndicator: renderModeratorIndicator,
             _participantId: participantId,
+            _videoMuted: videoMuted
+        } = this.props;
+        const indicators = [];
+
+        if (renderModeratorIndicator) {
+            indicators.push(<View style = { styles.moderatorIndicatorContainer }>
+                <ModeratorIndicator />
+            </View>);
+        }
+
+        if (!_isFakeParticipant) {
+            indicators.push(<View
+                style = { [
+                    styles.thumbnailTopIndicatorContainer,
+                    styles.thumbnailTopLeftIndicatorContainer
+                ] }>
+                <RaisedHandIndicator participantId = { participantId } />
+                { renderDominantSpeakerIndicator && <DominantSpeakerIndicator /> }
+            </View>);
+            indicators.push(<View
+                style = { [
+                    styles.thumbnailTopIndicatorContainer,
+                    styles.thumbnailTopRightIndicatorContainer
+                ] }>
+                <ConnectionIndicator participantId = { participantId } />
+            </View>);
+            indicators.push(<Container style = { styles.thumbnailIndicatorContainer }>
+                { audioMuted && <AudioMutedIndicator /> }
+                { videoMuted && <VideoMutedIndicator /> }
+                { isScreenShare && <ScreenShareIndicator /> }
+            </Container>);
+        }
+
+        return indicators;
+    }
+
+    /**
+     * Implements React's {@link Component#render()}.
+     *
+     * @inheritdoc
+     * @returns {ReactElement}
+     */
+    render() {
+        const {
+            _isScreenShare: isScreenShare,
+            _isFakeParticipant,
+            _participantId: participantId,
             _participantInLargeVideo: participantInLargeVideo,
             _pinned,
             _styles,
-            _videoMuted: videoMuted,
             disableTint,
             height,
             renderDisplayName,
                             <DisplayNameLabel participantId = { participantId } />
                         </Container>
                 }
-                { renderModeratorIndicator
-                    && <View style = { styles.moderatorIndicatorContainer }>
-                        <ModeratorIndicator />
-                    </View>
-                }
-                {
-                    !_isFakeParticipant
-                        && <View
-                            style = { [
-                                styles.thumbnailTopIndicatorContainer,
-                                styles.thumbnailTopLeftIndicatorContainer
-                            ] }>
-                            <RaisedHandIndicator participantId = { participantId } />
-                            { renderDominantSpeakerIndicator && <DominantSpeakerIndicator /> }
-                        </View>
-                }
                 {
-                    !_isFakeParticipant
-                        && <View
-                            style = { [
-                                styles.thumbnailTopIndicatorContainer,
-                                styles.thumbnailTopRightIndicatorContainer
-                            ] }>
-                            <ConnectionIndicator participantId = { participantId } />
-                        </View>
-                }
-                {
-                    !_isFakeParticipant
-                        && <Container style = { styles.thumbnailIndicatorContainer }>
-                            { audioMuted && <AudioMutedIndicator /> }
-                            { videoMuted && <VideoMutedIndicator /> }
-                            { isScreenShare && <ScreenShareIndicator /> }
-                        </Container>
+                    this._renderIndicators()
                 }
             </Container>
         );

react/features/filmstrip/components/native/TileView.js

     onClick: Function
 };
 
+/**
+ * An empty array. The purpose of the constant is to use the same reference every time we need an empty array.
+ * This will prevent unnecessary re-renders.
+ */
+const EMPTY_ARRAY = [];
+
 /**
  * Implements a React {@link PureComponent} which displays thumbnails in a two
  * dimensional grid.
             itemVisiblePercentThreshold: 30
         };
         this._flatListStyles = {
-            ...styles.flatList
+            ...styles.flatListTileView
         };
         this._contentContainerStyles = {
             ...styles.contentContainer
 
         if (this._flatListStyles.minHeight !== _height || this._flatListStyles.minWidth !== _width) {
             this._flatListStyles = {
-                ...styles.flatList,
+                ...styles.flatListTileView,
                 minHeight: _height,
                 minWidth: _width
             };
      */
     _getSortedParticipants() {
         const { _localParticipant, _remoteParticipants } = this.props;
-        const participants = [];
 
-        _localParticipant && participants.push(_localParticipant.id);
+        if (!_localParticipant) {
+            return EMPTY_ARRAY;
+        }
 
-        return [ ...participants, ..._remoteParticipants ];
+        return [ _localParticipant?.id, ..._remoteParticipants ];
     }
 
     _renderThumbnail: Object => Object;

react/features/filmstrip/components/native/styles.js

     },
 
     /**
-     * The styles for the FlatList.
+     * The styles for the FlatList component in stage view.
      */
-    flatList: {
+    flatListStageView: {
+        flexGrow: 0
+    },
+
+    /**
+     * The styles for the FlatList component in tile view.
+     */
+    flatListTileView: {
         flex: 0
     },
 
         right: 4
     },
 
-    /**
-     * The style of the scrollview containing the remote thumbnails.
-     */
-    scrollView: {
-        flexGrow: 0
-    },
-
     /**
      * The style of a participant's Thumbnail which renders either the video or
      * the avatar of the associated participant.

react/features/filmstrip/middleware.native.js

  */
 MiddlewareRegistry.register(store => next => action => {
     if (action.type === PARTICIPANT_LEFT) {
+        // This have to be executed before we remove the participant from features/base/participants state in order to
+        // remove the related thumbnail component before we need to re-render it. If we do this after next()
+        // we will be in sitation where the participant exists in the remoteParticipants array in features/filmstrip
+        // but doesn't exist in features/base/participants state which will lead to rendering a thumbnail for
+        // non-existing participant.
         updateRemoteParticipantsOnLeave(store, action.participant?.id);
     }