Just a developer, a simple guy.
Usually it is preferable to use a <BrowserRouter>, but if your website will be hosted on a server that only serves static files, then <HashRouter> is a good solution.
Fix: Never mutate values used as React props or state. You can do this with the help of array spreading, object spreading, immutability-helper, immutablejs, etc. Good luck…
Mistakes are a part of the journey. With every mistake, there is a lesson to be learned. Learn to embrace them.