patch 8.2.3415: Vim9: not all function argument types are properly checked

Problem:    Vim9: Not all function argument types are properly checked.
Solution:   Add and improve argument type checks. (Yegappan Lakshmanan,
            closes #8839)
diff --git a/src/terminal.c b/src/terminal.c
index d0d791c..eb9e780 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -5663,7 +5663,7 @@
 {
     if (in_vim9script()
 	    && (check_for_string_arg(argvars, 0) == FAIL
-		|| check_for_dict_arg(argvars, 1) == FAIL))
+		|| check_for_opt_dict_arg(argvars, 1) == FAIL))
 	return;
 
     term_load_dump(argvars, rettv, FALSE);