[Widget snippet] Javascript selector error because selector with square brackets

[TranQuyetThang]

Hi @jtsternberg
I tried to set up follow cmb2 widget snippet (just copy and run).
But error Javascript appear when i click button Add or Upload File::

Uncaught Error: Syntax error, unrecognized expression: label[for=widget-cmb2-widget-boilerplate-slug[2][image]]

I think, should change selector:
From: label[for=widget-cmb2-widget-boilerplate-slug[2][image]]
To: label[for="widget-cmb2-widget-boilerplate-slug[2][image]"]

[tw2113]

Not seeing this anywhere in the repo, in terms of where the js part is from. At least if still an issue, can you point me to where this selector is found at