[BUGFIX] In the overwrite mode it isn't possible to set an empty value

Classes/Service/FileService.php

@@ -201,9 +201,15 @@ abstract class FileService extends AbstractService {
 		if (!empty($value) || (($langKey === 'default' && !$forceDel))) {
 			$this->localLang[$langKey][$constant] = $value;
 		} elseif (isset($this->localLang[$langKey][$constant])) {
+			if ($this->session->getDataByKey('editingMode') === 'override' &&
+				isset($this->localLang[$langKey][$constant])
+			) {
+				$this->localLang[$langKey][$constant] = "";
+			} else {
 				unset($this->localLang[$langKey][$constant]);
 			}
 		}
+	}
 
 	/**
 	 * returns origin