Column '{colId}' classWhen['{class}'] must be a function or a rule string.

Warnings reference › classwhen-type:*:*

Identifier

classwhen-type:*:*

Raised by

The grid (rendering)

Since

1.0.1

What happened

The value for that class was neither a function, a rule string nor a boolean, so the entry was dropped and the class is never applied. false, null and undefined are the supported way to disable an entry and are not reported.

The fix

Give the entry a rule string, a predicate function, or true to apply the class to every cell.

Reference

Covered in full at the API reference.