Show /NICK in input box if erroneous nickname is chosen.

IdealIRC/IRC.cpp

@@ -685,6 +685,9 @@ void IRC::onMsgNumeric(const IRCPrefix& /*sender*/, const std::string& num, cons
         }
     }
 
+    /*
+     * Numeric responses handled separately from message displaying
+     */
     if (num == Numeric::ERR_NICKNAMEINUSE && !isOnline()) {
         auto& conf = ConfigMgr::instance();
         auto altNick = conf.connection("AltNickname");
@@ -696,6 +699,10 @@ void IRC::onMsgNumeric(const IRCPrefix& /*sender*/, const std::string& num, cons
         }
     }
 
+    else if (num == Numeric::ERR_ERRORNEUSNICKNAME && !isOnline()) {
+        getStatus().getInputBox().setText("/NICK ");
+    }
+
     else if (num == Numeric::RPL_ENDOFWHOIS) {
         m_receiveWhoisToCurrentWindow = false;
     }