Type the following

inter

A completion list should come up, and the interface keyword will be selected. Completion entry details will show for the completion item.

Press enter to complete the keyword. This triggers formatting as well, and the call crashes.

Error: Debug Failure. False expression:
at assert (:1143:17)
at formatOnEnter (:22246:13)
at getFormattingEditsAfterKeystroke (:26833:17)
at Anonymous function (:27863:17)
at simpleForwardCall (:27643:9)
at forwardJSONCall (:27657:13)
at forwardJSONCall (:27688:13)
at getFormattingEditsAfterKeystroke (:27861:13)