patch 9.1.1325: tests: not checking error numbers properly

Problem:  tests: not checking error numbers properly.
Solution: Add a trailing comma to avoid matching a different error
          number with the same prefix (zeertzjq)

closes: #17159

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_usercommands.vim b/src/testdir/test_usercommands.vim
index fe08b95..deea5df 100644
--- a/src/testdir/test_usercommands.vim
+++ b/src/testdir/test_usercommands.vim
@@ -326,13 +326,13 @@
       vim9script
       com! -complete=file DoCmd :
   END
-  call v9.CheckScriptFailure(lines, 'E1208', 2)
+  call v9.CheckScriptFailure(lines, 'E1208:', 2)
 
   let lines =<< trim END
       vim9script
       com! -nargs=0 -complete=file DoCmd :
   END
-  call v9.CheckScriptFailure(lines, 'E1208', 2)
+  call v9.CheckScriptFailure(lines, 'E1208:', 2)
 
   com! -nargs=0 DoCmd :
   call assert_fails('DoCmd x', 'E488:')