Fix Flutter App & Build iOS

My Flutter app used to compile and run flawlessly, but I left it untouched for a few months. When I opened it today it throws several errors and will not launch. I have not updated Flutter itself or any pub dependencies since the last successful build, so the project is sitting on older versions... (Budget: $10 - $15 USD, Jobs: Debugging, Flutter, iOS Development, iPhone, Mobile App Development, Objective C, Swift, Xcode)