The NestedStringResourceLoader ignores hard-coded default values and throws a MissingResourceException.
The default value provided here actually gets lost in the call hierarchy in `Localizer.getString()` (line 232). That seems to be ok because the code there seems to expect that any code it calls will not take into account the `ThrowExceptionOnMissingResource` setting (at least that is what I infer from the method name `getStringIgnoreSettings`. However, again further down the hierarchy, `NestedStringResourceLoader.handleMissingKey()` (line 166) is called which throws a MissingResourceException and defies the default-value handling code in `Localizer.getString()`.
Here is a stack trace: