6.1.3 !argument_type

This error is raised by variables and methods (i.e. behaviour) and various other methods to indicate that the n-th argument is not of the requested type. Argument counting starts after the selection:

send(@display, inform, 'Hello %s', universe).
                      ^^1-st^^  ^^2-nd^^

See also

- !argument_count
- !bad_selector