CONSOLE MESSAGE: line 139: Exception thrown as a part of test

PASS Upgrading a custom element must enqueue attributeChangedCallback on each attribute 
PASS Upgrading a custom element not must enqueue attributeChangedCallback on unobserved attributes 
PASS Upgrading a custom element must enqueue connectedCallback if the element in the document 
PASS Upgrading a custom element must enqueue attributeChangedCallback before connectedCallback 
PASS Upgrading a custom element must not invoke attributeChangedCallback and connectedCallback when the element failed to upgrade