REBOL 3 Errors: expect-arg

A function was provided an argument of a datatype it wasn't expecting.

Message:

[:arg1 "expected" :arg2 "argument of type:" :arg3]

Example:

f: func [b [block!]][probe b]
filter-error try [f "string"]
** Script Error: f expected b argument of type: block
** Where: f "string"