patch 8.2.3056: Vim9: using default value in lambda gives confusing error

Problem:    Vim9: using default value in lambda gives confusing error.
Solution:   Pass "default_args" on the first pass to get the arguments.
            (closes #8455)
diff --git a/src/userfunc.c b/src/userfunc.c
index e2e745c..cedd37b 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -1222,7 +1222,7 @@
     s = *arg + 1;
     ret = get_function_args(&s, equal_arrow ? ')' : '-', NULL,
 	    types_optional ? &argtypes : NULL, types_optional, evalarg,
-						 NULL, NULL, TRUE, NULL, NULL);
+					NULL, &default_args, TRUE, NULL, NULL);
     if (ret == FAIL || skip_arrow(s, equal_arrow, &ret_type, NULL) == NULL)
     {
 	if (types_optional)