dictfmt segfault on debug

[Huy-Ngo]

When I run dictfmt -fD basename, the command segfaulted. This happens on both version 1.13.0 and 1.13.1.

I can reproduce on two systems: NixOS (compiled with glibc) and Alpine Linux (compiled with musl)

Here's the core dump (on NixOS) if it's of any help:

       Message: Process 3121 (dictfmt) of user 1001 dumped core.

                Module linux-vdso.so.1 with build-id 0b88b3964e233abb62b7754e737470a5bf449e12
                Module ld-linux-x86-64.so.2 with build-id 7689db54fdcebb0522a62647a2eece153cf24178
                Module libm.so.6 with build-id 5f6c67b079df8f9aa6c17f41ecf836a23999a858
                Module libc.so.6 with build-id cd4b41522c8f722f5054a0316d293e6d85eef07d
                Module libmaa.so.3 without build-id.
                Module libz.so.1 without build-id.
                Module dictfmt without build-id.
                Stack trace of thread 3121:
                #0  0x00007fcff25f6e89 _IO_ftell (libc.so.6 + 0x73e89)
                #1  0x000000000040497d fmt_newheadword (dictfmt + 0x497d)
                #2  0x0000000000403489 main (dictfmt + 0x3489)
                #3  0x00007fcff25ac237 __libc_start_call_main (libc.so.6 + 0x29237)
                #4  0x00007fcff25ac2f5 __libc_start_main@@GLIBC_2.34 (libc.so.6 + 0x292f5)
                #5  0x00000000004038a1 _start (dictfmt + 0x38a1)
                ELF object binary architecture: AMD x86-64