port UBFIXes from emerald

src/field_effect.c

@@ -3666,8 +3666,16 @@ static void Task_MoveDeoxysRock_Step(u8 taskId)
     case 0:
         data[4] = sprite->pos1.x << 4;
         data[5] = sprite->pos1.y << 4;
-        data[6] = ((data[2] << 4) - data[4]) / data[8];
-        data[7] = ((data[3] << 4) - data[5]) / data[8];
+
+        // UB: Possible divide by zero
+        #ifdef UBFIX
+        #define DIVISOR (data[8] ? data[8] : 1);
+        #else
+        #define DIVISOR (data[8])
+        #endif
+
+        data[6] = ((data[2] << 4) - data[4]) / DIVISOR;
+        data[7] = ((data[3] << 4) - data[5]) / DIVISOR;
         data[0]++;
         // fallthrough
     case 1: