Been awhile since my last time playing GameBoy Advance (GBA). Year 2000+ I have experienced playing the real GBA. Nowadays, I just play GBA using VisualBoyAdvance on Windows 10 and this software works perfectly!
But there is an error when you load Pokemon Emerald ROM. I have googled the error and found the solution here (http://ngemu.com/threads/pokemon-emerald-white-screen.185305/). What a surprise that it just simple fix/solution, just change the Save Type > Flash 128K, then the ROM now load successfully.
I downloaded my GBA ROM from EmuParadise.Me (https://www.emuparadise.me/Nintendo_Gameboy_Advance_ROMs/31). Have fun!