Runthrough linting fixes

Finalized runthrough fixing linting issues. The app is still compiling and seems to work just as before. Number of issues was brought down from:

(current) Main: ✖ 3426 problems (2799 errors, 627 warnings)

to: (branch) lint_fixing: ✖ 2796 problems (2267 errors, 529 warnings)

Apologies for another massive MR 🙈