Bugfix: compute the current theme each time we want to know which theme is beeing used

src/App.php

@@ -1095,9 +1095,10 @@ class App
 			return '';
 		}
 
-		if (!$this->current_theme) {
-			$this->computeCurrentTheme();
-		}
+		//// @TODO Compute the current theme only once (this behavior has
+		/// already been implemented, but it didn' work well -
+		/// https://github.com/friendica/friendica/issues/5092)
+		$this->computeCurrentTheme();
 
 		return $this->current_theme;
 	}