patch 8.2.4872: Vim9: no error for using an expression only

Problem:    Vim9: no error for using an expression only at the script level
            when followed by an empty line.
Solution:   Do not check the line number but whether something follows.
            (closes #10357)

src/testdir/test_vim9_cmd.vim

@@ -650,6 +650,20 @@ def Test_use_register()
   END
   v9.CheckDefAndScriptFailure(lines, 'E1207:', 2)
 
+  lines =<< trim END
+      @a = 'echo "text"'
+      @a
+
+  END
+  v9.CheckDefAndScriptFailure(lines, 'E1207:', 2)
+
+  lines =<< trim END
+      @a = 'echo "text"'
+      @a
+          # comment
+  END
+  v9.CheckDefAndScriptFailure(lines, 'E1207:', 2)
+
   lines =<< trim END
       @/ = 'pattern'
       @/