eraseCell method
Implementation
void eraseCell(int index, CursorStyle style) {
final offset = index * _cellSize;
_data[offset + _cellForeground] = style.foreground;
_data[offset + _cellBackground] = style.background;
_data[offset + _cellAttributes] = style.attrs & ~CellAttr.protected;
_data[offset + _cellContent] = 0;
_setUnderlineColor(index, style.underlineColor);
_combiningCharacters.remove(index);
}