[Glitch] Fix “X new items” not showing up for slow mode on empty timelines

Port 2d5addde03 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/components/scrollable_list/index.jsx

@@ -344,7 +344,7 @@ class ScrollableList extends PureComponent {
           {footer}
         </Scrollable>
       );
-    } else if (isLoading || childrenCount > 0 || hasMore || !emptyMessage) {
+    } else if (isLoading || childrenCount > 0 || numPending > 0 || hasMore || !emptyMessage) {
       scrollableArea = (
         <Scrollable fullscreen={fullscreen} ref={this.setRef} onMouseMove={this.handleMouseMove}>
           {prepend}