Sorry for the very long response.

I've reproduced this issue a few times and attached lldb to see where it blocked.

All attempts were the same:

> (lldb) bt all
> * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
>   * frame #0: 0x00007ff817ed220a libsystem_kernel.dylib`__read_nocancel + 10
>     frame #1: 0x00007ff817de5fb9 libsystem_c.dylib`_sread + 16
>     frame #2: 0x00007ff817de5f68 libsystem_c.dylib`__srefill1 + 24
>     frame #3: 0x00007ff817de39b8 libsystem_c.dylib`__svfscanf_l + 2059
>     frame #4: 0x00007ff817e39a2f libsystem_c.dylib`scanf + 196
>     frame #5: 0x000000010ea0800a emacsql-sqlite`main + 234
>     frame #6: 0x00000001173db52e dyld`start + 462
> (lldb)


--
wbr, Kirill