TWEWY crashes during main opening cutscene

[Stevoisiak]

Issue: After starting a new game of The World Ends With You (US), MelonDS crashes during the main opening cutscene.

Steps to reproduce:

1. Start a new game of The World Ends With You.
2. Advance through cutscenes and dialogue.
3. Play through tutorials on scanning and combat.
4. Advance dialogue until main into cutscene plays.

Expected result: The cutscene plays properly.

Actual result: The cutscene crashes 15 seconds in with glitched visuals and stuttering audio.

System:

• MelonDS 0.9.2
• Windows 10 Pro (20H2)
• AMD Ryzen 5 5600X
• NVIDIA GeForce GTX 1070
• ROM MD5: 3BFC95753B37C97A6D30018630048A51

Video: (Issue occurs at 3:45) https://user-images.githubusercontent.com/1330770/121636499-fff1ce00-ca55-11eb-89dc-65f94bd577d9.mp4

[endrift]

This used to happen in medusa in the same place. It ended up being due to...a race condition of some sort leading to a null pointer write, but since that address is ITCM that's actually being used, it crashes like this in exactly this same spot. I think I fixed it with cartridge timing changes, but I forget.

E] Dug up the medusa bug report: https://github.com/mgba-emu/mgba/issues/583

[RSDuck]

duplicate of #380

[tuy360]

Also had this error.