Allows you to display a validation error message when a form is submitted.
Can only be nested within an m-form
Supports output patterns with double square brackets
Examples
<m-form>
<m-form-error>[[#error]]incorrect <b>[[title]]</b><br />[[/error]]</m-form-error>
</m-form><m-form>
<m-form-error></m-form-error>
</m-form>