Two different ESE TJAs trigger `System.DivideByZeroException` when converting

[vivaria]

While testing ESE using the develop branch (TakoTako + tja2fumen 0.5.2), I noticed that two songs result in DivideByZero exceptions when converted using TJAConvert.exe:

• Garyoutensei.zip
• Issei Fuubi.zip

These songs convert fine using just tja2fumen directly, though.

I'll try to debug exactly what happens and report back. :)