Add feedback to incorrect usage of the /w command and the /whispers split (#3477)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

CHANGELOG.md

@@ -45,6 +45,8 @@
 - Minor: Add search to emote popup. (#3404)
 - Minor: Messages can now be highlighted by subscriber or founder badges. (#3445)
 - Minor: Add workaround for multipart emoji as described in [the RFC](https://mm2pl.github.io/emoji_rfc.pdf). (#3469)
+- Minor: Add feedback when using the whisper command `/w` incorrectly. (#3439)
+- Minor: Add feedback when writing a non-command message in the `/whispers` split. (#3439)
 - Bugfix: Fix Split Input hotkeys not being available when input is hidden (#3362)
 - Bugfix: Fixed colored usernames sometimes not working. (#3170)
 - Bugfix: Restored ability to send duplicate `/me` messages. (#3166)

src/controllers/commands/CommandController.cpp

@@ -933,6 +933,11 @@ QString CommandController::execCommand(const QString &textNoEmoji,
                 appendWhisperMessageWordsLocally(words);
                 sendWhisperMessage(text);
             }
+            else
+            {
+                channel->addMessage(
+                    makeSystemMessage("Usage: /w <username> <message>"));
+            }
 
             return "";
         }
@@ -980,6 +985,13 @@ QString CommandController::execCommand(const QString &textNoEmoji,
         }
     }
 
+    if (!dryRun && channel->getType() == Channel::Type::TwitchWhispers)
+    {
+        channel->addMessage(
+            makeSystemMessage("Use /w <username> <message> to whisper"));
+        return "";
+    }
+
     return text;
 }