Digging into this now. You're correct; it's an oversight in the program. This should definitely use a FREEFILE handle here, to prevent issues. All the other save image routines do, but this one in particular (the JPG save image code) had a hard coded file handle of 1 it relied upon, which, as you said, can cause issues.
I'm also surprised that line 685 didn't toss issues for you, as it was a CLOSE statement, without any parameters to it. As it currently exists, it'll close every open file out there in your program, and not just the JPG file which it creates. That's doing just a weeee bit more than intended.
A fix for these will be coming soon(tm).