shada: fix write E5004 error on exit

Fix the problem of failing to write shada when the global variable contains
Funcref or Partial.

src/nvim/shada.c

@@ -2676,6 +2676,13 @@ static ShaDaWriteResult shada_write(ShaDaWriteDef *const sd_writer,
       if (name == NULL) {
         break;
       }
+      switch (vartv.v_type) {
+        case VAR_FUNC:
+        case VAR_PARTIAL:
+          continue;
+        default:
+          break;
+      }
       typval_T tgttv;
       tv_copy(&vartv, &tgttv);
       ShaDaWriteResult spe_ret;

test/functional/shada/errors_spec.lua

@@ -494,14 +494,6 @@ $
     eq(0, exc_exec('wshada! ' .. shada_fname))
   end)
 
-  it('errors when a funcref is stored in a variable', function()
-    nvim_command('let F = function("tr")')
-    nvim_command('set shada+=!')
-    eq('\nE5004: Error while dumping variable g:F, itself: attempt to dump function reference'
-       .. '\nE574: Failed to write variable F',
-       redir_exec('wshada'))
-  end)
-
   it('errors when a self-referencing list is stored in a variable', function()
     nvim_command('let L = []')
     nvim_command('call add(L, L)')

test/functional/shada/variables_spec.lua

@@ -121,15 +121,27 @@ describe('ShaDa support code', function()
        meths.get_var('NESTEDVAR'))
   end)
 
-  it('errors and writes when a funcref is stored in a variable',
+  it('ignore when a funcref is stored in a variable',
   function()
     nvim_command('let F = function("tr")')
     meths.set_var('U', '10')
     nvim_command('set shada+=!')
-    eq('Vim(wshada):E5004: Error while dumping variable g:F, itself: attempt to dump function reference',
-       exc_exec('wshada'))
-    meths.set_option('shada', '')
-    reset('set shada+=!')
+    nvim_command('wshada')
+    reset()
+    nvim_command('set shada+=!')
+    nvim_command('rshada')
+    eq('10', meths.get_var('U'))
+  end)
+
+  it('ignore when a partial is stored in a variable',
+  function()
+    nvim_command('let P = { -> 1 }')
+    meths.set_var('U', '10')
+    nvim_command('set shada+=!')
+    nvim_command('wshada')
+    reset()
+    nvim_command('set shada+=!')
+    nvim_command('rshada')
     eq('10', meths.get_var('U'))
   end)