Allow smaller stack trace depth

[focusaurus]

Every exception I hit prints enough output to scroll several screens off my screen requiring a lengthy scrollback process to see the actual error message. It looks like from this comment maybe you had thought about truncating the output at some point? I futzed with *print-length* and *print-level* but I don't think they address my main concern, which is the total number of lines printed, most of which are not useful to my typical development flow.