fix: correctly report error position on unknown directive without values

[kasiaMarek]

This PR changes positions in unrecognised directives errors.
fixes: #3389

Previously

Errors used to be reported on values:

Unrecognized directive: wrong.directive with values: value
//> using wrong.directive value
                          ^^^^^

which resulted also in two errors for two values:

Unrecognized directive: wrong.directive with values: value1, value2
//> using wrong.directive value1 value2
                          ^^^^^^
Unrecognized directive: wrong.directive with values: value1, value2
//> using wrong.directive value1 value2
                                 ^^^^^^

and incorrect position for no values.

Now

We use directive position for error report:

Unrecognized directive: wrong.directive with values: value1, value2
//> using wrong.directive value1 value2
          ^^^^^^^^^^^^^^^

[Gedochao]

LGTM!