entered characters missing from search term with :Ag, control characters added to search term

[snoblenet]

• I have read through the manual page (man fzf)
• I have the latest version of fzf
• I have searched through the existing issues

Info

• OS
  • Linux
  • Mac OS X
  • Windows
  • Etc.
• Shell
  • bash
  • zsh
  • fish

Mac OS X 10.15.3
fzf 0.20.0 (brew)
ag 2.2.0 with +jit +lxma +zlib
alacritty @ 8a83340
neovim stable 0.4.3 (bottled), HEAD

Problem / Steps to reproduce

Type :Ag then fdes to search for tests focused with fdescribe.

Sometimes this works but sometimes you just see fs instead of fdes. When you give up and press the up arrow key to look for a match, fs then changes to fdes but instead of scrolling up through the search results, every arrow key press adds special characters to the search term. Also trying to quit the window with <CTRL-C> or similar also sometimes just adds special characters to the search term. Illustration below.

I'm not 100% sure if I've seen the same with other fzf commands but if I notice this later I'll leave a comment below.

[junegunn]

Please check if you can reproduce the problem with a minimal Vim configuration like so

nvim -Nu <(curl https://gist.githubusercontent.com/junegunn/6936bf79fedd3a079aeb1dd2f3c81ef5/raw)

[snoblenet]

I did not experience the problem the minimal configuration.

A few observation:

• I don't always experience it with my configuration either -- it comes and goes
• The minimal configuration was much, much faster -- to open, to filter, and to update filtering when you update the search term
• There may be a subtle connection between the behaviour and speed, in that I don't think I ever experience this locally if I wait a few seconds after typing :Ag<CR> before typing the initial search term