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)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index fb7aedd..01bf2c1 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -6884,6 +6884,8 @@
     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 @@
 	    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);