Fix pinning; first-in-position channel

Author: arnautov-anton

src/components/ChannelList/hooks/useMemberUpdatedListener.ts

@@ -38,8 +38,9 @@ export const useMemberUpdatedListener = <SCG extends ExtendableGenerics>({
           newChannels.splice(targetChannelIndex, 1);
         }
 
-        const lastPinnedChannelIndex = findLastPinnedChannelIndex({ channels: newChannels }) ?? 0;
-        const newTargetChannelIndex = lastPinnedChannelIndex + 1;
+        const lastPinnedChannelIndex = findLastPinnedChannelIndex({ channels: newChannels });
+        const newTargetChannelIndex =
+          typeof lastPinnedChannelIndex === 'number' ? lastPinnedChannelIndex + 1 : 0;
 
         // skip re-render if the position of the channel does not change
         if (currentChannels[newTargetChannelIndex] === targetChannel) {