mapper4 There seems to be a problem

I tried to run some roms that support mapper4 mmc3, but some roms are gray screen. I found a similar project on github, but I don't know how to improve jsnes with it.
rom parameter:MMC3 rom: 16 PRG bank(s), 32 CHR bank(s)
project address:[NesJS mmc3 Mapper](https://github.com/elzo-d/NesJs/blob/master/mappers/mmc3.js)

Start by reproducing the gray screen with the reported MMC3 ROM parameters: 16 PRG banks and 32 CHR banks. Compare jsnes's mapper4 behavior with the linked NesJS mmc3.js implementation. Done means affected mapper4/MMC3 ROMs run without producing a gray screen.

Written by the indexing model from the issue text.