debug.c: Attempts to close stderr

[USSX-Hares]

https://github.com/jleffler/soq/blob/bb84e0704fb66a558fbcf507f43e76a7a547930e/src/libsoq/debug.c#L57C1-L59C1

        if (debugfp != stdin && debugfp != stdout && debugfp != stderr)
            fclose(debugfp);
        debugfp = dbfp;

In main:

    db_setfileptr(stderr);

Here, debugfp is initialized with 0 and then is attempted to close in db_setfileptr, leading to SEGFAULT