might want to update that when hotplugging joysticks, too

src/libui_sdl/main.cpp

@@ -436,6 +436,16 @@ int EmuThreadFunc(void* burp)
             if (!Joystick && (SDL_NumJoysticks() > 0))
             {
                 Joystick = SDL_JoystickOpen(0);
+                if (Joystick)
+                {
+                    njoybuttons = SDL_JoystickNumButtons(Joystick);
+                    if (joybuttons) delete[] joybuttons;
+                    if (njoybuttons)
+                    {
+                        joybuttons = new Uint8[njoybuttons];
+                        memset(joybuttons, 0, sizeof(Uint8)*njoybuttons);
+                    }
+                }
             }
 
             // poll input