weblint does not accept input from stdin

weblint says it can accept input from stdin but then fails in actually doing so.

$ weblint --help
weblint v2.26
Usage: weblint [filename or url]... (filename - reads STDIN)
    --help This message
    --context[=n] Show the offending line (and n surrounding lines)

    Error types: (default: all on)
    --[no]structure Structural issues, like unclosed tag pairs
    --[no]helper Helper issues, like missing HEIGHT & WIDTH
    --[no]fluff Fluff that can be removed, like bad tag attributes
    --only Turns off all other error types, as in --only --fluff

$ cat public/404.html|weblint -
Can't open -: No such file or directory at /usr/bin/weblint line 60.

$ echo test | weblint -
Can't open -: No such file or directory at /usr/bin/weblint line 60.

$ apt policy weblint-perl
weblint-perl:
  Installed: 2.26+dfsg-1
  Candidate: 2.26+dfsg-1
  Version table:
 *** 2.26+dfsg-1 500
        500 http://de.archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
        500 http://de.archive.ubuntu.com/ubuntu bionic/universe i386 Packages
        100 /var/lib/dpkg/status