Dynamic entity reference fields try to use a default field formatter that doesn't exist

The module provides a "dynamic_entity_reference_default" formatter, but then tries to define "dynamic_entity_reference_label" as the default formatter (which doesn't exist). This can cause problems when rendering the field, as well as when using the field UI.

From looking at the code, I think this only affects the Drupal 7 version of the module (not Drupal 8) but I haven't tested that.