Steps to reproduce the issue

Add to any grid admin layout using JHTML like this
JHTML::_('grid.boolean', $i, $row->important,'helloworlds.important','helloworlds.unimportant');

Expected result

The row is selected and the task is invoked

Actual result

Error JSON.decode is not a function into JavaScript console

System information (as much as possible)

Joomla 3.9.15 and staging

Additional comments

A component using the boolean field to illustrate this bug.
Joomla-3-Hello-World-Component_0.16.zip

I try will prepare the pull request to fix it