Increase debugability with better error message

[benjamin-dreux]

See the following exemple

.option()
    .text("$")
    .attrValue("CAD")
    .<FileGeneralInformationsEditModel>dynamic((option, model) -> 
        option.attrSelected(model.requestedAmountCurrency().equals("CAD"))
    )
.__()

Have a view containing this will produce the following error message

java.lang.IllegalStateException: Cannot add attributes after!!!
	at htmlflow.visitor.HtmlVisitor.visitAttribute(HtmlVisitor.java:179) ~[htmlflow-4.3.jar:na]
	at org.xmlet.htmlapifaster.ElementVisitor.visitAttributeValue(ElementVisitor.java:1729) ~[htmlApiFaster-1.0.15.jar:na]
	at org.xmlet.htmlapifaster.Option.attrValue(Option.java:65) ~[htmlApiFaster-1.0.15.jar:na]
	at get.simple.today.lender.generalInformations.FileGeneralInformationsEditView.requestedAmountField(FileGeneralInformationsEditView.java:400) ~[classes/:na]

Sure there is the class name/method and line number. But the exception message could be enhanced to help user scan faster the error.

For exemple the following would be a enhancement in my opinion
Cannot add attributes (name of the attribute) after the current element opening tag (name of the tag) has been completed