patch 8.2.3249: Vim9: error for re-imported function with default argument

Problem:    Vim9: error for re-imported function with default argument.
Solution:   Do not check argument type if it is still unknown. (closes #8653)
diff --git a/src/vim9execute.c b/src/vim9execute.c
index 5c59c5b..f453af7 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -1271,7 +1271,7 @@
 	return NULL;
     }
     sv = ((svar_T *)si->sn_var_vals.ga_data) + sref->sref_idx;
-    if (!equal_type(sv->sv_type, sref->sref_type))
+    if (!equal_type(sv->sv_type, sref->sref_type, 0))
     {
 	emsg(_(e_script_variable_type_changed));
 	return NULL;