Runtime Error

ClassValueRequired

No value was provided to the data-class attribute.

The data-class attribute must have a value, representing either an expression (if a key is provided), or an object of key-value pairs, where the keys are class names and the values are expressions.

Example:

1<div data-class-hidden="$foo"></div>

Alternative syntax:

1<div data-class="{hidden: foo}"></div>

See the docs for the data-class attribute.