fix(psalm): Resolve static analysis errors for ExApp backend

- Classifier: generator return type void -> null (bare return yields null)
- AdminController: avoid RiskyTruthyFalsyComparison via explicit (bool) cast
- ExAppService: mark final; suppress Mixed* from the optional AppAPI
  PublicFunctions calls (UndefinedClass dependency) and cast the error
  message operand to string

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: szaimen

lib/Classifiers/Classifier.php

@@ -203,7 +203,7 @@ public function classifyFiles(string $model, array $queueFiles, int $timeout): \
 	 * @param int $timeout
 	 * @param int $startTime
 	 * @return \Generator
-	 * @psalm-return \Generator<int, string, mixed, void>
+	 * @psalm-return \Generator<int, string, mixed, null>
 	 * @throws \ErrorException|\RuntimeException
 	 */
 	private function runLocally(string $model, array $paths, int $timeout, int $startTime): \Generator {
@@ -297,7 +297,7 @@ private function runLocally(string $model, array $paths, int $timeout, int $star
 	 * @param list<string> $paths
 	 * @param int $timeout
 	 * @return \Generator
-	 * @psalm-return \Generator<int, string, mixed, void>
+	 * @psalm-return \Generator<int, string, mixed, null>
 	 * @throws \ErrorException
 	 */
 	private function runExApp(string $model, array $paths, int $timeout): \Generator {

lib/Controller/AdminController.php

@@ -236,7 +236,7 @@ public function exapp(): JSONResponse {
 		$appId = $this->settingsService->getSetting('exapp.id');
 		$exApp = $this->exAppService->getExApp($appId);
 
-		if ($exApp === null || !($exApp['enabled'] ?? false)) {
+		if ($exApp === null || !(bool)($exApp['enabled'] ?? false)) {
 			return new JSONResponse(['exapp' => false]);
 		}
 

lib/Service/ExAppService.php

@@ -27,7 +27,7 @@
  * the app_api app is not installed, so recognize keeps working with the local
  * node.js backend.
  */
-class ExAppService {
+final class ExAppService {
 	private const APP_API_APP_ID = 'app_api';
 	private const APP_API_PUBLIC_FUNCTIONS = 'OCA\\AppAPI\\PublicFunctions';
 
@@ -56,7 +56,10 @@ private function getPublicFunctions(): ?object {
 			return null;
 		}
 		try {
-			/** @psalm-suppress UndefinedClass */
+			/**
+			 * @psalm-suppress UndefinedClass AppAPI is an optional dependency
+			 * @psalm-suppress MixedReturnStatement
+			 */
 			return \OCP\Server::get(self::APP_API_PUBLIC_FUNCTIONS);
 		} catch (\Throwable $e) {
 			$this->logger->warning('Could not load AppAPI PublicFunctions', ['exception' => $e]);
@@ -74,7 +77,11 @@ public function getExApp(string $appId): ?array {
 			return null;
 		}
 		try {
-			/** @psalm-suppress UndefinedClass */
+			/**
+			 * @psalm-suppress UndefinedClass AppAPI is an optional dependency
+			 * @psalm-suppress MixedReturnStatement
+			 * @psalm-suppress MixedMethodCall
+			 */
 			return $publicFunctions->getExApp($appId);
 		} catch (\Throwable $e) {
 			$this->logger->warning('Could not query ExApp ' . $appId, ['exception' => $e]);
@@ -104,13 +111,18 @@ public function request(string $appId, string $route, string $method = 'POST', a
 			throw new \RuntimeException('AppAPI is not available, cannot reach ExApp ' . $appId);
 		}
 
-		/** @psalm-suppress UndefinedClass */
+		/**
+		 * @psalm-suppress UndefinedClass AppAPI is an optional dependency
+		 * @psalm-suppress MixedAssignment
+		 * @psalm-suppress MixedMethodCall
+		 */
 		$response = $publicFunctions->exAppRequest($appId, $route, null, $method, $params, $options);
 
 		if (is_array($response) && isset($response['error'])) {
-			throw new \RuntimeException('ExApp request to ' . $appId . $route . ' failed: ' . $response['error']);
+			throw new \RuntimeException('ExApp request to ' . $appId . $route . ' failed: ' . (string)$response['error']);
 		}
 
+		/** @psalm-suppress MixedReturnStatement */
 		return $response;
 	}
 }