LibKeyboard: Don't assert on failure

Author: https://github.com/BenWiederhake
Commit: 0e3408d4d6
Pull-request: https://github.com/SerenityOS/serenity/pull/5192
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/bcoles
Reviewed-by: https://github.com/emanuele6
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibKeyboard/CharacterMap.h

@@ -39,8 +39,8 @@ namespace Keyboard {
 class CharacterMap {
 
 public:
-    CharacterMap(const String& map_name);
     CharacterMap(const String& map_name, const CharacterMapData& map_data);
+    static Optional<CharacterMap> load_from_file(const String& file_name);
 
 #ifndef KERNEL
     int set_system_map();