fix(keymap setup): do not crash on vim.fn.extend to explain the user keymap config has changed

lua/nvim-tree/view.lua

@@ -112,6 +112,11 @@ function M._wipe_rogue_buffer()
   end
 end
 
+local function warn_wrong_mapping()
+  local warn_str = "Wrong configuration for keymaps, refer to the new documentation. Keymaps setup aborted"
+  require'nvim-tree.utils'.echo_warning(warn_str)
+end
+
 -- set user options and create tree buffer (should never be wiped)
 function M.setup()
   M.View.side = vim.g.nvim_tree_side or M.View.side
@@ -137,14 +142,20 @@ function M.setup()
   if vim.g.nvim_tree_disable_default_keybindings == 1 then
     M.View.bindings = user_mappings
   else
-    M.View.bindings = vim.fn.extend(M.View.bindings, user_mappings)
+    ok, result = pcall(vim.fn.extend, M.View.bindings, user_mappings)
+    if not ok then
+      -- TODO: remove this in a few weeks
+      warn_wrong_mapping()
+      return
+    else
+      M.View.bindings = result
+    end
   end
 
   for _, b in pairs(M.View.bindings) do
     -- TODO: remove this in a few weeks
     if type(b) == "string" then
-      local warn_str = "Wrong configuration for keymaps, refer to the new documentation. User keymaps setup aborted"
+      warn_wrong_mapping()
-      require'nvim-tree.utils'.echo_warning(warn_str)
       break
     end
     if type(b.key) == "table" then