ensure we always return an array from Request::getParams

Signed-off-by: Robin Appelman <robin@icewind.nl>

lib/private/AppFramework/Http/Request.php

@@ -358,7 +358,7 @@ public function getParam(string $key, $default = null) {
 	 * @return array the array with all parameters
 	 */
 	public function getParams(): array {
-		return $this->parameters;
+		return is_array($this->parameters) ? $this->parameters : [];
 	}
 
 	/**