The code returns the following error:

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

Check the render method of `ControlPanel`.

Revise the code to address the error.

参考这张图内的staff paper功能,参考视觉风格,帮我调整目前的视觉和功能布局,请你在生成的过程中把不相关的功能剔除