fix: add return type to providePresentation function

Signed-off-by: Elizabeth Danzberger <lizzy7128@tutanota.de>

lib/Service/InitialStateService.php

@@ -60,7 +60,7 @@ public function provideDocument(Wopi $wopi, array $params): void {
 		$this->provideOptions();
 	}
 
-	public function providePresentation(bool $startPresentation = false) {
+	public function providePresentation(bool $startPresentation = false): void {
 		$this->initialState->provideInitialState('document', [
 			'startPresentation' => $startPresentation,
 		]);