I think Constructor here is executing before the Injection is completed for the properties, hence no resource resolver is being injected. That's where @PostConstruct  annotated method is useful when we want to utilize the injected objects in the processing.

create cq:htmlTag node as nt:unstructured,create property cq:tagName and leave it blank.This seems perfect solution for removing default wrapper from a component.This node can be used to set any class and to change the wrapper element.