fix: add nil check to git status

[hlmtre]

Requisite config:

local nvim_tree_setup = function()
  require('nvim-tree').setup({
    on_attach = on_attach,
    diagnostics = {
      enable = true,
    },
    update_focused_file = {
      enable = true,
      update_root = false,
    },
    respect_buf_cwd = false,
    sync_root_with_cwd = false,
    view = {
      width = 40,
      side = 'right',
      --mappings = {
      --  custom_only = false,
      --  list = {
      --    { key = { '<CR>', '<Tab>' }, action = 'edit' },
      --  },
      --},
    },
  })
end

Occasionally, with the above config, nvim-tree will spit out the following error message:

node.lua attempt to index local 'status' a nil value

creating a nice big traceback of the complaint and stealing focus briefly. You can immediately press q and leave it and go back to what you were doing, but it happens a few times in a couple seconds, then chills out.

Working theory: I think there were points at which the git status of a node wasn't set, and nvim-tree would still try to get its git status, leading to ... local 'status' a nil value. This change simply quietly does not return anything at the time of that check (but we don't care, it'll get run again soon).

Error executing vim.schedule lua callback: .../nvim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/node.lua:19: attempt to index local 'status' (a nil value)
stack traceback:
        .../nvim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/node.lua:19: in function 'get_status'
        .../nvim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/node.lua:46: in function 'update_git_status'
        ...vim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/reload.lua:54: in function 'update_parent_statuses'
        ...vim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/reload.lua:180: in function 'callback'
        ...vim/lazy/nvim-tree.lua/lua/nvim-tree/explorer/reload.lua:28: in function 'callback'
        ...share/nvim/lazy/nvim-tree.lua/lua/nvim-tree/git/init.lua:111: in function 'callback'
        ...are/nvim/lazy/nvim-tree.lua/lua/nvim-tree/git/runner.lua:194: in function 'callback'
        ...are/nvim/lazy/nvim-tree.lua/lua/nvim-tree/git/runner.lua:101: in function 'on_finish'
        ...are/nvim/lazy/nvim-tree.lua/lua/nvim-tree/git/runner.lua:113: in function ''
        vim/_editor.lua: in function <vim/_editor.lua:0>

[Akmadan23]

Thank you for finding this one! Missing nil checks can be really annoying sometimes

[alex-courtis]

Great catch!

nil resulting from this function i.e. node.git_status is checked / handled in all obvious places so we are OK.