Perl 6 error message: Malformed UTF-8 in block <unit>

For slurp, if you have some idea about encoding, you can also add encoding specifically.

From documentation (https://docs.perl6.org/routine/slurp):

my $text_contents   = slurp "path/to/file", enc => "latin1";

I used it today for a stupid file encoded in ISO-8859-1.

If you do not specify an encoding when opening a file, it will assume utf8. Apparently, the file that you wish to open, contains bytes that cannot be interpreted as UTF-8. Hence the error message.

Depending on what you want to do with the file contents, you could either set the :bin named parameter, to have the file opened in binary mode. Or you could use the special utf8-c8 encoding, which will assume UTF-8 until it encounters bytes it cannot encode: in that case it will generate temporary code points.

See https://docs.raku.org/language/unicode#UTF8-C8 for more information.