PVS-Studio warning V595 for yasm

unsigned long
elf_secthead_write_to_file(FILE *f, elf_secthead *shead,
                           elf_section_index sindex)
{
    unsigned char buf[SHDR_MAXSIZE], *bufp = buf;
    shead->index = sindex;

    if (shead == NULL)
        yasm_internal_error("shead is null");
  ....
}

This suspicious code was found in yasm project by PVS-Studio static code analyzer.
Warning message is:
V595 The 'shead' pointer was utilized before it was verified against nullptr. Check lines: 672, 674. elf.c 672

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