You could test this.
I manually caused an infinite recursion at the same location as the other crash report and I got a crash report with 511 frames. Frames numbered 9 to 510 are all the same, and since 510 is the last one, it looks like it's cut off. Otherwise the frames look very similar to the crash report downloaded by Xcode.
Thread 4 Crashed:: Dispatch queue: com.apple.root.user-initiated-qos
0 CoreFoundation 0x1837f5084 __CFStringEncodeByteStream + 76
1 Foundation 0x184901558 -[NSString(NSStringOtherEncodings) getBytes:maxLength:usedLength:encoding:options:range:remainingRange:] + 260
2 libswiftCore.dylib 0x1931cf194 _NSStringCopyBytes(_:encoding:into:) + 124
3 libswiftCore.dylib 0x1931d67f0 _StringGuts._foreignCopyUTF8(into:) + 80
4 libswiftCore.dylib 0x1931d7bc8 _StringGuts._foreignConvertedToSmall() + 68
5 libswiftCore.dylib 0x1931d7b44 _StringGuts.append(_:) + 1232
6 libswiftCore.dylib 0x19316ba80 String.write<A>(to:) + 56
7 libswiftCore.dylib 0x19300bef0 DefaultStringInterpolation.appendInterpolation<A>(_:) + 72
8 MyApp 0x1000e4538 String.appendingPathComponent(_:) + 924 (PathAdditions.swift:75)
9 MyApp 0x100119138 Snapshot.renameFile(_:to:) + 696 (Snapshot+Modify.swift:135)
10 MyApp 0x10011915c Snapshot.renameFile(_:to:) + 732 (Snapshot+Modify.swift:135)
...
510 MyApp 0x10011915c Snapshot.renameFile(_:to:) + 732 (Snapshot+Modify.swift:135)
And it's also the same exception type:
Exception Type: EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000170027fd8
Exception Codes: 0x0000000000000002, 0x0000000170027fd8
Termination Reason: Namespace SIGNAL, Code 10 Bus error: 10
Terminating Process: exc handler [66786]
VM Region Info: 0x170027fd8 is in 0x170024000-0x170028000; bytes after start: 16344 bytes before end: 39
REGION TYPE START - END [ VSIZE] PRT/MAX SHRMOD REGION DETAIL
Stack 16ff9c000-170024000 [ 544K] rw-/rwx SM=PRV thread 3
---> STACK GUARD 170024000-170028000 [ 16K] ---/rwx SM=NUL ... for thread 4
Stack 170028000-1700b0000 [ 544K] rw-/rwx SM=PRV thread 4
I guess we solved the mystery? Probably the backtrace got cut off along the way between the user and my Xcode instance.
Thank you very much for your help!