docs: public static JavaScriptException throwCustomError(Context cx, Scriptable scope, String constructorName,
              String message) {
        int[] linep = { 0 };
        String filename = Context.getSourcePositionFromStack(linep);
        final Scriptable error =  cx.newObject(scope, constructorName,
          new Object[] { message, filename, Integer.valueOf(linep[0]) });
        return new JavaScriptException(error, filename, linep[0]);
      }