Workflow failing when text field has "Valid internet address or hostname" option set and the value is not valid in the vSphere web console

When I choose the option to check the data of the string field to be a valid hostname or address and there are bad characters the vSphere web console does not seem to catch this when entered into the form and then blows up most ungracefully at runtime.  Is this a known issue or do I need to put a bug report in?