Bug report

MDCList will try to toggle checkboxes even when this specific list item does not have a checkbox

Steps to reproduce

1. Create an MDCList with two items where the first item contains a checkbox, and the second does not.
2. It may be necessary to call mdcList.layout()
3. Click on the second item
4. See error in console TypeError: Cannot read property 'checked' of null

Actual behavior

mdc list assumes that all items contain checkboxes. and tries read property checked from it. If there is no checkbox, the document selector returns null and the assertion fails at:

Uncaught TypeError: Cannot read property 'checked' of null
    at Object.isCheckboxCheckedAtIndex (component.ts:265)
    at MDCListFoundation.toggleCheckboxAtIndex_ (foundation.ts:647)
    at MDCListFoundation.setSelectedIndexOnAction_ (foundation.ts:639)
    at MDCListFoundation.handleClick (foundation.ts:372)
    at MDCList.handleClickEvent (component.ts:410)

Expected behavior

MDC should not try to toggle the checkbox it doesn't exist

Your Environment:

Possible solution

Gracefully accessing the property at "component.ts:265" is a possible soution. I.e. toggleEl?.checked
This could also be needed in other places where listItem.querySelector<HTMLInputElement>(strings.CHECKBOX_SELECTOR); or similar is used.

Another solution could be to fix the todo at