Fix bug when using object storage

Author: iolate

lib/Service/Note.php

@@ -37,6 +37,10 @@ public function getCategory() : string {
 
 	public function getContent() : string {
 		$content = $this->file->getContent();
+		// blank files return false when using object storage as primary storage
+		if ($content === false && $this->file->getSize() === 0) {
+			$content = '';
+		}
 		if (!is_string($content)) {
 			throw new \Exception('Can\'t read file content.');
 		}