First - DONT PANIC!
Second - realize that IRCC officers are humans and they know people filling these up are also humans. So relax...its just one form.
What to do about it. Quickly - send a Webform. identify that you have found the mistake. its isolated to only One form..give the form number, the exact page it happened on etc. And confirm your correct name - which matches all the other docs in the application.
Keep it simple and concise. Its not a big issue as its only on 1 form.