fix: footer

[subfuzion]

Fix for production / docker build lint error:

$ npm run build
. . .
#16 4.794 ./src/pages/index.tsx:28:14
#16 4.794 Type error: 'Footer' cannot be used as a JSX component.
#16 4.794   Its return type 'Element | undefined' is not a valid JSX element.
#16 4.794     Type 'undefined' is not assignable to type 'Element | null'.
#16 4.794 
#16 4.794   26 |             <GameControls />
#16 4.794   27 |             <Inventory />
#16 4.794 > 28 |             <Footer />
#16 4.794      |              ^
#16 4.794   29 |           </>
#16 4.794   30 |         )}
#16 4.794   31 |       </main>