ArrayIndexOutOfBoundsException when recognizing hand-drawn image

[biotech7]

when trying to recognize example image(url: https://github.com/ncats/molvec/blob/master/test/hand-drawn.png), rising exception of ArrayIndexOutOfBoundsException. It's more likely related to Raster but failed to trace back.
codes to reproduce:
BufferedImage image = ImageIO.read(....); String molFileStr = Molvec.ocr(image);