[CLNP-7306]Fixed a bug that caused a runtime exception when leaving or deleting a channel (#1355)

[fix]: Fixed a bug that caused a runtime exception when leaving or
deleting a channel

Fixes [CLNP-7306](https://sendbird.atlassian.net/browse/CLNP-7306)

### Changelogs
- Fixed a bug that caused a runtime exception when leaving or deleting a
channel

### Checklist

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creating the PR. If unsure, ask the members.
This is a reminder of what we look for before merging your code.

- [x] **All tests pass locally with my changes**
- [ ] **I have added tests that prove my fix is effective or that my
feature works**
- [ ] **Public components / utils / props are appropriately exported**
- [ ] I have added necessary documentation (if appropriate)


## External Contributions

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[CLNP-7306]:
https://sendbird.atlassian.net/browse/CLNP-7306?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Author: danney-chun

src/modules/ChannelSettings/context/hooks/useChannelHandler.ts

@@ -31,13 +31,17 @@ export const useChannelHandler = ({
       onUserLeft: (channel, user) => {
         if (compareIds(channel?.url, channelUrl)) {
           logger.info('ChannelSettings: onUserLeft', { channel, user });
-          forceUpdateUI();
+          if (user.userId !== sdk.currentUser?.userId) {
+            forceUpdateUI();
+          }
         }
       },
       onUserBanned: (channel, user) => {
         if (compareIds(channel?.url, channelUrl) && channel.isGroupChannel()) {
           logger.info('ChannelSettings: onUserBanned', { channel, user });
-          forceUpdateUI();
+          if (user.userId !== sdk.currentUser?.userId) {
+            forceUpdateUI();
+          }
         }
       },
     });

src/modules/ChannelSettings/context/hooks/useSetChannel.ts

@@ -42,6 +42,7 @@ function useSetChannel({
         }
 
         setLoading(true);
+
         const groupChannel = await sdk.groupChannel.getChannel(channelUrl);
         if (!signal.aborted) {
           logger.info('ChannelSettings | useSetChannel: fetched group channel', groupChannel);

src/modules/GroupChannel/context/hooks/useGroupChannel.ts

@@ -77,7 +77,7 @@ export const useGroupChannel = () => {
 
     if (state.currentChannel && !state.hasNext()) {
       state.resetNewMessages();
-      if (!state.disableMarkAsRead) {
+      if (!state.disableMarkAsRead && state.currentChannel.myMemberState !== 'none') {
         markAsReadScheduler.push(state.currentChannel);
       }
     }
@@ -157,16 +157,16 @@ export const useGroupChannel = () => {
     scrollToBottom,
   });
 
-  const setCurrentChannel = useCallback((channel: GroupChannel) => {
+  const setCurrentChannel = useCallback((channel: GroupChannel | null) => {
     store.setState(state => ({
       ...state,
       currentChannel: channel,
       fetchChannelError: null,
       quoteMessage: null,
       animatedMessageId: null,
-      nicknamesMap: new Map(
+      nicknamesMap: channel ? new Map(
         channel.members.map(({ userId, nickname }) => [userId, nickname]),
-      ),
+      ) : new Map(),
     }), true);
   }, []);