REBOL 3 Errors: invalid-path

An attempt was made to access a block or object value using a path that did not exist within that block or object.

Message:

["Invalid path value:" :arg1]

Example:

blk: [a "a" b "b"]
filter-error try [print blk/c]
** Script Error: Invalid path value: c
** Where: print blk/c

obj: make object! [a: "a" b: "b"]
filter-error try [print obj/d]
** Script Error: Invalid path value: d
** Where: print obj/d