Fix chat rejoined receiving repeated messages

browser/vue-flow/src/components/chat.vue

@@ -104,6 +104,8 @@ export default {
     },
 
     sendChatJoin () {
+      // Clear messages here
+      this.events = []
       this.$flowService.chatJoin(this.handle, this.$route.params.sessId)
     },
     sendChatRename () {