Easy motion shows error when jumping to brackets and backslash

[nnkken]

Describe the bug
When using easy motion, functions which allows jumping to specified symbols (e.g. <leader><leader>f, <leader><leader>s), some symbols (which have special meaning in regexp) are not supported and will generate error (about invalid regexp) when used.

When ()[?\ are used, error message are shown.

When $ is used, position marks are shown at incorrect position (end of line).

When ^ is used, the Vim plugin is stuck and not responding to any inputs.

To Reproduce
Steps to reproduce the behavior:

1. turn easy motion on in settings
2. suppose we have text (bracket) [square bracket] \backslash ?question_mark ^start $end
3. input <leader><leader>f( or <leader><leader>f) or <leader><leader>f[ or <leader><leader>f\ or <leader><leader>f? or <leader><leader>f^ or <leader><leader>f$

Expected behavior
symbols are shown at the corresponding position, or jump to the symbols directly when there is no other matches

Screenshots

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.4.0
• VSCode version: 1.33.1
• OS: Windows 10 Pro 64-bit

Additional context
Add any other context about the problem here.

[J-Fields]

This was fixed with #3911