Why not fail if /usr/bin/file fails?

Hi.
I'm trying to build https://aur.archlinux.org/packages/mingw-w64-libunistring.

Libtool thinks that the installed dependency libiconv.dll.a has unknown type and refuses to build libunistring dll.

The libtool script calls `file` internally to detect the type, but it suppresses the error output which makes it hard to troubleshoot:

    func_win32_libid ()
    {
      $debug_cmd
    
      win32_libid_type=unknown
      win32_fileres=`file -L $1 2>/dev/null`
      case $win32_fileres in

If I call `file` directly I can see the error:

    [il@arch lib]$ fakeroot file -L /usr/x86_64-w64-mingw32/lib/libiconv.dll.a
    /usr/bin/fakeroot: line 178: 962263 Bad system call         FAKEROOTKEY=$FAKEROOTKEY LD_LIBRARY_PATH="$PATHS" LD_PRELOAD="$LIB" "$@"

Yet make finishes successfully and an invalid package is built.

Is there any reason to ignore non-zero exit code from external programs called by libtool? I don't understand.