Update runtime files.
diff --git a/runtime/doc/message.txt b/runtime/doc/message.txt
index 638d7c7..65cd8df 100644
--- a/runtime/doc/message.txt
+++ b/runtime/doc/message.txt
@@ -1,4 +1,4 @@
-*message.txt* For Vim version 8.1. Last change: 2018 Dec 30
+*message.txt* For Vim version 8.1. Last change: 2019 Apr 04
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -703,11 +703,13 @@
This happens when an Ex command with mandatory argument(s) was executed, but
no argument has been specified.
- *E474* *E475* >
+ *E474* *E475* *E983* >
Invalid argument
Invalid argument: {arg}
+ Duplicate argument: {arg}
-An Ex command has been executed, but an invalid argument has been specified.
+An Ex command or function has been executed, but an invalid argument has been
+specified.
*E488* >
Trailing characters