patch 8.2.3269: Vim9: wrong argument check for partial

Problem:    Vim9: wrong argument check for partial. (Naohiro Ono)
Solution:   Handle getting return type without arguments. Correct the minimal
            number of arguments for what is included in the partial.
            (closes #8667)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 23a39aa..ff0d33a 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -932,22 +932,27 @@
     return &t_void;
 }
     static type_T *
-ret_repeat(int argcount UNUSED, type_T **argtypes)
+ret_repeat(int argcount, type_T **argtypes)
 {
+    if (argcount == 0)
+	return &t_any;
     if (argtypes[0] == &t_number)
 	return &t_string;
     return argtypes[0];
 }
 // for map(): returns first argument but item type may differ
     static type_T *
-ret_first_cont(int argcount UNUSED, type_T **argtypes)
+ret_first_cont(int argcount, type_T **argtypes)
 {
-    if (argtypes[0]->tt_type == VAR_LIST)
-	return &t_list_any;
-    if (argtypes[0]->tt_type == VAR_DICT)
-	return &t_dict_any;
-    if (argtypes[0]->tt_type == VAR_BLOB)
-	return argtypes[0];
+    if (argcount > 0)
+    {
+	if (argtypes[0]->tt_type == VAR_LIST)
+	    return &t_list_any;
+	if (argtypes[0]->tt_type == VAR_DICT)
+	    return &t_dict_any;
+	if (argtypes[0]->tt_type == VAR_BLOB)
+	    return argtypes[0];
+    }
     return &t_any;
 }
 
@@ -987,9 +992,9 @@
 }
 
     static type_T *
-ret_remove(int argcount UNUSED, type_T **argtypes)
+ret_remove(int argcount, type_T **argtypes)
 {
-    if (argtypes != NULL)
+    if (argcount > 0)
     {
 	if (argtypes[0]->tt_type == VAR_LIST
 		|| argtypes[0]->tt_type == VAR_DICT)
@@ -2446,6 +2451,7 @@
  * Call the "f_retfunc" function to obtain the return type of function "idx".
  * "argtypes" is the list of argument types or NULL when there are no
  * arguments.
+ * "argcount" may be less than the actual count when only getting the type.
  */
     type_T *
 internal_func_ret_type(int idx, int argcount, type_T **argtypes)