As the subtitle suggests, the splash art itself is the reason why Steam Input glitched when starting the game, causing a crash. The on-launch splash art has been removed from the game to fix this. You may now boot the game with Steam Input enabled without crashing.
The irony is that the splash art is a fundamental feature/option of Gamemaker as an engine, and is not something I actually programmed, so I still have no idea as to how or why this interaction occurred, let alone the fact that it was possible.
Either way, apologies for the inconvenience this issue caused!