patch 8.2.2371: Vim9: crash when using types in :for with unpack

Problem:    Vim9: crash when using types in :for with unpack.
Solution:   Check for skip_var_list() failing. Pass include_type to
            skip_var_one(). Skip type when compiling. (closes #7694)

src/evalvars.c

@@ -1019,7 +1019,7 @@ skip_var_list(
 	for (;;)
 	{
 	    p = skipwhite(p + 1);	// skip whites after '[', ';' or ','
-	    s = skip_var_one(p, FALSE);
+	    s = skip_var_one(p, include_type);
 	    if (s == p)
 	    {
 		if (!silent)
@@ -1067,11 +1067,14 @@ skip_var_one(char_u *arg, int include_type)
 	return arg + 2;
     end = find_name_end(*arg == '$' || *arg == '&' ? arg + 1 : arg,
 				   NULL, NULL, FNE_INCL_BR | FNE_CHECK_START);
+
+    // "a: type" is declaring variable "a" with a type, not "a:".
+    // Same for "s: type".
+    if (end == arg + 2 && end[-1] == ':')
+	--end;
+
     if (include_type && in_vim9script())
     {
-	// "a: type" is declaring variable "a" with a type, not "a:".
-	if (end == arg + 2 && end[-1] == ':')
-	    --end;
 	if (*end == ':')
 	    end = skip_type(skipwhite(end + 1), FALSE);
     }

src/testdir/test_vim9_script.vim

@@ -2060,6 +2060,12 @@ def Test_for_loop()
     total += nr
   endfor
   assert_equal(6, total)
+
+  var res = ""
+  for [n: number, s: string] in [[1, 'a'], [2, 'b']]
+    res ..= n .. s
+  endfor
+  assert_equal('1a2b', res)
 enddef
 
 def Test_for_loop_fails()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2371,
 /**/
     2370,
 /**/

src/vim9compile.c

@@ -6884,6 +6884,8 @@ compile_for(char_u *arg_start, cctx_T *cctx)
     int		idx;
 
     p = skip_var_list(arg_start, TRUE, &var_count, &semicolon, FALSE);
+    if (p == NULL)
+	return NULL;
     if (var_count == 0)
 	var_count = 1;
 
@@ -7018,6 +7020,8 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	    generate_STORE(cctx, ISN_STORE, var_lvar->lv_idx, NULL);
 	}
 
+	if (*p == ':')
+	    p = skip_type(skipwhite(p + 1), FALSE);
 	if (*p == ',' || *p == ';')
 	    ++p;
 	arg = skipwhite(p);