fix: chat user instructions

Signed-off-by: Jana Peper <jana.peper@nextcloud.com>

Author: janepie

lib/Controller/ChattyLLMController.php

@@ -133,6 +133,9 @@ public function newSession(int $timestamp, ?string $title = null): JSONResponse
 			'chat_user_instructions',
 			Application::CHAT_USER_INSTRUCTIONS,
 		);
+		if ($userInstructions === '') {
+			$userInstructions = Application::CHAT_USER_INSTRUCTIONS;
+		}
 		$userInstructions = str_replace('{user}', $user->getDisplayName(), $userInstructions);
 
 		try {
@@ -737,6 +740,9 @@ public function checkTitleGenerationTask(int $taskId, int $sessionId): JSONRespo
 					'chat_user_instructions_title',
 					Application::CHAT_USER_INSTRUCTIONS_TITLE,
 				);
+				if ($userInstructions === '') {
+					$userInstructions = Application::CHAT_USER_INSTRUCTIONS_TITLE;
+				}
 				$userInstructions = str_replace('{user}', $user->getDisplayName(), $userInstructions);
 				$title = str_replace($userInstructions, '', $taskOutput);
 				$title = str_replace('"', '', $title);