patch 8.2.3645: Vim9: The "no effect" error is not given for all registers

Problem:    Vim9: The "no effect" error is not given for all registers.
Solution:   Include any character following '@'. (closes #8779)

src/testdir/test_vim9_cmd.vim

@@ -556,7 +556,34 @@ def Test_use_register()
       @a = 'echo "text"'
       @a
   END
-  CheckDefAndScriptFailure(lines, 'E1207:')
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+
+  lines =<< trim END
+      @/ = 'pattern'
+      @/
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+
+  lines =<< trim END
+      &opfunc = 'nothing'
+      &opfunc
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+  &opfunc = ''
+
+  lines =<< trim END
+      &l:showbreak = 'nothing'
+      &l:showbreak
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+  &l:showbreak = ''
+
+  lines =<< trim END
+      &g:showbreak = 'nothing'
+      &g:showbreak
+  END
+  CheckDefAndScriptFailure(lines, 'E1207:', 2)
+  &g:showbreak = ''
 enddef
 
 def Test_environment_use_linebreak()