delete.type autocompletion skips over types

[ceedubs]

Add a type like unique type Foo = Foo Nat and then in ucm type delete.type Fo<TAB>. It completes to delete.type Foo. and if you hit enter it displays the curious message I don't know how to parse.

Instead it should autocomplete to delete.type Foo.

Separately that error message should probably be fixed.

[sixfourtwelve]

Happy to take, seems the issues I like most are yours @ceedubs :)