patch 8.2.2190: Vim9: crash when compiled with EXITFREE

Problem:    Vim9: crash when compiled with EXITFREE.
Solution:   Check that df_ufunc is not NULL.

src/testdir/test_vim9_func.vim

@@ -2011,5 +2011,27 @@ def Test_opfunc()
   nunmap <F3>
 enddef
 
+" this was crashing on exit
+def Test_nested_lambda_in_closure()
+  var lines =<< trim END
+      vim9script
+      def Outer()
+          def g:Inner()
+              echo map([1, 2, 3], {_, v -> v + 1})
+          enddef
+          g:Inner()
+      enddef
+      defcompile
+      writefile(['Done'], 'XnestedDone')
+      quit
+  END
+  if !RunVim([], lines, '--clean')
+    return
+  endif
+  assert_equal(['Done'], readfile('XnestedDone'))
+  delete('XnestedDone')
+enddef
+
+
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2190,
 /**/
     2189,
 /**/

src/vim9compile.c

@@ -8081,9 +8081,10 @@ delete_instr(isn_T *isn)
 	    {
 		dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
 					       + isn->isn_arg.funcref.fr_func;
+		ufunc_T *ufunc = dfunc->df_ufunc;
 
-		if (func_name_refcount(dfunc->df_ufunc->uf_name))
-		    func_ptr_unref(dfunc->df_ufunc);
+		if (ufunc != NULL && func_name_refcount(ufunc->uf_name))
+		    func_ptr_unref(ufunc);
 	    }
 	    break;