Add message box when emulator fails to load invalid or corrupted file.

[SirQuartz]

This pull request implements a message box when the user attempts to open an invalid or corrupt file format, either by dragging and dropping or by opening it through the file system.

Before, the emulator would just immediately terminate if this happened, which is something that should be avoided whenever possible because it's not particularly constructive or informative for the user. In this case it is completely avoidable, so it might as well be avoided.

With this pull request the emulator will no longer immediately crash, it will instead show a message box that actually tells the user what went wrong.

https://user-images.githubusercontent.com/62965063/194938414-00e7e7f6-d651-4974-b842-ccfc37cdab57.mp4