FIX: prevents chat to enter in endless loop when getting 404 (#18867)

Doing DOM operations in finally would cause them to happen even when the request was a failure. Consequence of these DOM operations would be new request, which would also end up in a 404, and so on.

This commit simply moves the DOM operations in the then block where it should be safe to make.

plugins/chat/assets/javascripts/discourse/components/chat-live-pane.js

@@ -243,6 +243,12 @@ export default Component.extend({
             return;
           }
           this.setMessageProps(messages, fetchingFromLastRead);
+
+          if (this.targetMessageId) {
+            this.highlightOrFetchMessage(this.targetMessageId);
+          }
+
+          this.focusComposer();
         })
         .catch(this._handleErrors)
         .finally(() => {
@@ -252,12 +258,6 @@ export default Component.extend({
 
           this.chat.set("messageId", null);
           this.set("loading", false);
-
-          if (this.targetMessageId) {
-            this.highlightOrFetchMessage(this.targetMessageId);
-          }
-
-          this.focusComposer();
         });
     });
   },