Assert Violation

Stream: general

[Namdak Tonpa]

LEAN ASSERTION VIOLATION
File: /tmp/lean-20180823-20161-4hyzri/lean-3.4.1/src/frontends/lean/elaborator.cpp
Line: 3167
Task: /Users/maxim/depot/groupoid/lean/homotopy_theory/formal/i_category/drag.lean: homotopy_theory.cofibrations.drag_equiv
m_ctx.match(e, *val2)

Just catch in Reid Barton's code :-) Unfortunately non-reproducable.

[Reid Barton]

I've seen errors like this as well, not sure what caused them. I thought they were related to things like changing branches or mathlib versions. They seem to go away on their own