How can the printing a parser error rule be made to say the noun to which the error refers?
There’s no built-in way. The parser has failed to match any object in scope. There could be zero, one, or twelve objects elsewhere in the game which match that phrase, but the parser doesn’t have a list of them.
There’s an extension which does the extra work to find matching objects. (I don’t remember the name offhand. Possibly more than one.) However, you do have to think about which objects the player might reasonably know about.
If the player has typed a valid object, but not one they can see? The “Remembering” extension does a fairly good job of this, especially on Glulx. (Though strictly speaking it creates new valid actions instead of using parser errors.)
If you want to print the text which the parser failed on? You’ll have to go down to the I6 level for that, unfortunately, unless an extension already handles this.
Thanks guys. Unknown Word Error by Mike Ciul seems to do what I wanted.