patch 8.2.3907: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move error messages to errors.h.  Avoid duplicates.
diff --git a/src/testdir/test_user_func.vim b/src/testdir/test_user_func.vim
index 819a6bb..6eb8a0f 100644
--- a/src/testdir/test_user_func.vim
+++ b/src/testdir/test_user_func.vim
@@ -428,7 +428,7 @@
 
 " Test for deleting a function
 func Test_del_func()
-  call assert_fails('delfunction Xabc', 'E130:')
+  call assert_fails('delfunction Xabc', 'E117:')
   let d = {'a' : 10}
   call assert_fails('delfunc d.a', 'E718:')
   func d.fn()