fix: skip updateUserMessageReferences if channel is undefined

[arnautov-anton]

Description of the changes, What, Why and How?

Fixes an issue where apps would crash due missing state on undefined channel when trying to update userChannelReferences.

Error in question:

TypeError: Cannot read properties of undefined (reading 'state')
node_modules/stream-chat/dist/browser.es.js at line 6861:31

    _defineProperty(this, "_updateUserMessageReferences", function (user) {
      var refMap = _this.state.userChannelReferences[user.id] || {};

      for (var _channelID2 in refMap) {
        var _channel3 = _this.activeChannels[_channelID2];
        var state = _channel3.state;
        /** update the messages from this user. */

        state === null || state === void 0 ? void 0 : state.updateUserMessages(user);
      }
    });

[github-actions]

Size Change: +44 B (0%)

Total Size: 352 kB

Filename	Size	Change
dist/browser.es.js	76 kB	+10 B (0%)
dist/browser.full-bundle.min.js	46.4 kB	+8 B (0%)
dist/browser.js	76.9 kB	+9 B (0%)
dist/index.es.js	76 kB	+9 B (0%)
dist/index.js	77 kB	+8 B (0%)

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