LocalVariableTypesCalculator replaces some binary comparison nodes with RuntimeNodes depending on the types of their left and right sides. Since types can change between optimistic recompilations, it is possible that a BinaryNode is replaced by a RuntimeNode in a later compilation. Different nodes use different local slots, so the local slot layout may different between an initial optimistic version of a function and a recompiled restOf version of the function, causing the continuation handler to crash.

This happens in version 2.0.3 of the CoffeeScript compiler when running with optimistic types enabled.