Emulation fixes:

• GB: Fix savedata initialization (fixes #1478, #1478)
• GB: Fix SGB controller incrementing (fixes #1104)
• GB Audio: Improve channel 4 supersampling
• GB Printer: Reset printer buffer index after printing
• GB Audio: Deschedule channel 3 when disabled (fixes #1463)
• GB Audio: Deschedule channel 1 when disabled by sweep (fixes #1467)
• GB Video: Increment BCPS/OCPS even in mode 3 (fixes #1462)
• GBA Memory: Fix STM to VRAM (fixes #1430)
• GBA Memory: Fix STM/LDM to invalid VRAM
• GBA Video: Fix wrapped sprite mosaic clamping (fixes #1432)
• GBA Audio: Fix channel 4 aliasing (fixes #1265)

Other fixes:

• Core: Fix crashes if core directories aren’t set
• Core: Fix crash when exiting game with cheats loaded
• GBA: Set up GPIO mapping on null and ELF ROM regions (fixes #1481)
• GBA Cheats: Fix PARv3 Thumb hooks
• GBA Cheats: Fix value incrementing in CB slide codes (fixes #1501)
• Qt: Fix FPS target maxing out at 59.727 (fixes #1421)
• Qt: Cap audio buffer size to 8192 (fixes #1433)
• Qt: Fix race conditions initializing GDB stub
• Qt: Improve cheat view UX
• Libretro: Fix crash changing allowing opposing directions (hhromic)
• mGUI: Fix crash if last loaded ROM directory disappears (fixes #1466)
• Switch: Fix threading-related crash on second launch

Misc:

• Qt: Make mute menu option also toggle fast-forward mute (fixes #1424)
• Qt: Show error message if file failed to load