Fix various ESLint violations (#402)

## Description:

Fixes a number of ESLint violations. Although I have tested these
changes through the local dev server, I don't have a high confidence
that the testing is sufficient, as I am new to this codebase. This
change would benefit from heightened scrutiny.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

fake.neo

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>

src/client/InputHandler.ts

@@ -93,7 +93,7 @@ export class InputHandler {
 
   private alternateView = false;
 
-  private moveInterval: any = null;
+  private moveInterval: NodeJS.Timeout = null;
   private activeKeys = new Set<string>();
 
   private readonly PAN_SPEED = 5;