[Bug] Unable to submit checkbox responses containing commas

Steps to reproduce:

1. Create a form and add a checkbox type question.
2. Add a question option where the value contains a comma:

3. Preview the form, select the question option and submit the form.

_Expected behavior:_ The form submits successfully.
_Actual behavior:_ An error is displayed.

Note that it's fine for the text of the option to contain a comma, just not the value.