Command suggestion report "incorrect argument" when cursor is at the start of a node without suggestions

When typing arguments for a node that has no suggestions, now the command suggestion will just report and error instead of showing the string representation of the command node that the user is completing.

 

Before: (tested in 19w36a) when typing /help and a space, [<command>] text floats in the suggestion area

Now: (19w46a) when typing /help and a space, an error is displayed instead.

 

Same thing can be replicated to other argument nodes without proper suggestions, like the path or scale for /data get or /function etc.

This "incorrect argument" report IMO is partially intended as 19w46b aims to show this error in command blocks (trailing spaces do break commands in command blocks); imo a best solution is to have the error and the suggestion both presented on client, and only present the error for command function parsing.