Invalid enter mode if triggered from operator-pending mode

[backdround]

Description

If telescope triggered from operator-pending mode then it starts in normal mode instead of insert mode.

Precautions: The bug doesn't work when cursor on first line and first column.

Neovim version

NVIM v0.8.3
Build type: Release
LuaJIT 2.1.0-beta3

Operating system and version

Archlinux

Telescope version / branch / rev

telescope master / a3f17d3 / (after 0.1.1)

checkhealth telescope

telescope: require("telescope.health").check()
========================================================================
## Checking for required plugins
  - OK: plenary installed.
  - WARNING: nvim-treesitter not found.

## Checking external dependencies
  - OK: rg: found ripgrep 13.0.0
  - OK: fd: found fd 8.6.0

## ===== Installed extensions =====

## Telescope Extension: `fzf`
  - OK: lib working as expected
  - OK: file_sorter correctly configured
  - OK: generic_sorter correctly configured

Steps to reproduce

• nvim -u ./minimal.lua
• enter at least 2 characters
• place cursor on any character except first
• enter to operator-pending mode (by pressing d)
• trigger telescope (by <M-m>)

Expected behavior

The current mode is insert in just opened telescope window

Actual behavior

The current mode is normal in just opened telescope window

Minimal config

vim.cmd [[set runtimepath=$VIMRUNTIME]]
vim.cmd [[set packpath=/tmp/nvim/site]]
local package_root = '/tmp/nvim/site/pack'
local install_path = package_root .. '/packer/start/packer.nvim'
local function load_plugins()
  require('packer').startup {
    {
      'wbthomason/packer.nvim',
      {
        'nvim-telescope/telescope.nvim',
        requires = {
          'nvim-lua/plenary.nvim',
          { 'nvim-telescope/telescope-fzf-native.nvim', run = 'make' },
        },
      },
      -- ADD PLUGINS THAT ARE _NECESSARY_ FOR REPRODUCING THE ISSUE
    },
    config = {
      package_root = package_root,
      compile_path = install_path .. '/plugin/packer_compiled.lua',
      display = { non_interactive = true },
    },
  }
end
_G.load_config = function()
  require('telescope').setup()
  require('telescope').load_extension('fzf')
  -- ADD INIT.LUA SETTINGS THAT ARE _NECESSARY_ FOR REPRODUCING THE ISSUE
  local builtin = require("telescope.builtin")
  vim.keymap.set("o", "<M-m>", builtin.keymaps)
end
if vim.fn.isdirectory(install_path) == 0 then
  print("Installing Telescope and dependencies.")
  vim.fn.system { 'git', 'clone', '--depth=1', 'https://github.com/wbthomason/packer.nvim', install_path }
end
load_plugins()
require('packer').sync()
vim.cmd [[autocmd User PackerComplete ++once echo "Ready!" | lua load_config()]]

[backdround]

As i can say, if i wrap that line in vim.schedule, then all works fine: https://github.com/nvim-telescope/telescope.nvim/blob/a3f17d3baf70df58b9d3544ea30abe52a7a832c2/lua/telescope/pickers.lua#L442

Or If i wrap the mapping in vim.schedule, then all works fine too:

vim.keymap.set("o", "<M-m>", function()
  vim.schedule(builtin.keymaps)
end)

Could anyone give a guess why that is working that way?