Back in 1990, 3½-inch 1.44 MB micro floppy disks were snail-mailed to me — a Smalltalk/V 286 image file, sources file and change log; for a system I'd developed a year or two before.
The "image in its current state" had been saved with an open "Walkback Window" showing an exception.
I opened the debugger, identified and fixed the problem (iirc without needing to reshape any user data with become:) and resumed the exception; saved the image and change log to the micro floppy disks, and snail-mailed them back.
Apparently the users picked-up their work where they'd left-off, when they sent it to me.
"Chapter 8 Debugging"
http://rmod-files.lille.inria.fr/FreeBooks/SmalltalkVTutoria...