Memory Leaks & Compiler Optimization

[Daggerpov]

• Used [weak self] in closures, in conjunction with guard let self = self else { return } early-exits, to prevent memory leaks (from retain cycles between strongly referenced objects)
• Specified all variable types & function return types in all View Models, to optimize compiler (it won't have to implicitly figure out types)
• Changed test view model structs -> final class
  • See my Stackoverflow answer for why here: https://stackoverflow.com/a/79135798/13368695
• Laid groundwork to test for memory leaks, using Swift Testing de-initializers (similar to XCTest's "tear-down"), as I explain in the question on Stackoverflow: https://stackoverflow.com/q/79135797/13368695
• Will fix up current tests first, then implement this. For now, commented out #expects checks ("asserts" in XCTest terms):

[Daggerpov]

Currently, some of the tests need to be re-written (see screenshot below). Then, I'll implement the memory leak checking.