Ex "copy" command with ., -, or + (current, previous, or next line) at end of command stopped working

[patbl]

Describe the bug

In ex commands, you can use . to refer to the current line. So :5,.d means "delete everything between the 5th and current line (inclusive)." The dot doesn't work with the copy Ex command. It does, however, work with other commands, such as move and delete.

Also, ., -, and + work as long as they don't appear tat the very end of the command. So :.t0 will succesfully copy the current line to the top of the file. Because of this quirk, you can use -0 instead of . to reference the current line at the end of a copy command (e.g., :123t-0).

To Reproduce
Steps to reproduce the behavior:

1. Enable Neovim (vim.enableNeovim: true).
2. Open a file with some lines in it. Move to (e.g.) the third line.
3. Type :1copy. (or :1co., or :1t.; they are equivalent AFAIK).
4. See "E488: Trailing characters" error.

Expected behavior

The first line should be copied to the position after the current line.

Environment (please complete the following information):

• Extension (VsCodeVim) version: v1.21.7
• VSCode version: 1.60.0
• OS: 11.5.2 (also tested on Ubuntu 21.04)