You can clone with
This problem is caused due to the first let in swank.commands.basic /trace-fn-call.
This let isn't needed and when it is removed (and sum is renamed to frame) tracing works.
Interestingly the line is commented in the source with:
;; what is the point of this?
@emkayonline the "what is the point of this" comment was from me. Looking at the code again now I see that only user of that function is actually passing in a var rather than a symbol as you would expect from the arg name. So some conversion is required. swank-toggle-trace was using the name 'sym' for a var. untrace-all was also confused. I've just fixed all three.
fix #102 issues with swank-toggle-trace / untrace-all