public static void illegalStateIf(boolean tester, String msg, Object... args) {
        if (tester) {
            throw new IllegalStateException(S.fmt(msg, args));
        }
    }
public static void illegalStateIf ( boolean tester , String msg , Object ... args ) { if ( tester ) { throw new IllegalStateException ( S . fmt ( msg , args ) ) ; } }
Throws out an {@link IllegalStateException} with error message specified
if `tester` is `true`.

@param tester
when `true` then throw out the exception.
@param msg
the error message format pattern.
@param args
the error message format arguments.