Linestepping johntheripper on amd64 (with debuginfo and no optimization) was going fine, until the stacktrace started accumulating "null ()" in the top few frames of the stacktrace with the rest of the trace intact, and finally resulted in a single null (). Line stepping past this point resulted in a full stacktrace. I'll attach a screenshot in a sec.
Created attachment 1464 [details] Stepped into this stack trace