chore: add type annotations to (almost) all functions

lua/nvim-tree/explorer/sorters.lua

@@ -1,10 +1,11 @@
 local M = {}
 
+---@type table[string, fun(a: node, b: node): boolean]
 local C = {}
 
 --- Predefined comparator, defaulting to name
---- @param sorter string as per options
---- @return function
+---@param sorter string as per options
+---@return function
 local function get_comparator(sorter)
   return C[sorter] or C.name
 end
@@ -41,6 +42,11 @@ local function folders_or_files_first(a, b)
   end
 end
 
+---@param t table
+---@param first number
+---@param mid number
+---@param last number
+---@param comparator fun(a: table, b: table): boolean
 local function merge(t, first, mid, last, comparator)
   local n1 = mid - first + 1
   local n2 = last - mid
@@ -74,6 +80,10 @@ local function merge(t, first, mid, last, comparator)
   end
 end
 
+---@param t table
+---@param first number
+---@param last number
+---@param comparator fun(a: table, b: table): boolean
 local function split_merge(t, first, last, comparator)
   if (last - first) < 1 then
     return
@@ -137,6 +147,10 @@ function M.sort(t)
   end
 end
 
+---@param a table
+---@param b table
+---@param ignorecase boolean|nil
+---@return boolean
 local function node_comparator_name_ignorecase_or_not(a, b, ignorecase)
   if not (a and b) then
     return true