No, the grammar is fine. But when I copied and pasted the snippet of code into my editor, it didn’t paste the same as you typed it so it didn’t work. I think the font made the wrong symbols or something. I just looked back at what you wrote and then retyped it. Then it worked.
So no, not really a mistake. But maybe having the facility to type code (rather than the rtf the website uses) would fix the problem. Does that make sense?
Your English is fine, no worries. As the web becomes more and more international we’re all having to learn to read things outside of our native tongues. So much more web content is not in English nowadays and I enjoy the challenge of deciphering it!