AttributeError: 'NoneType' object has no attribute 'ravel'

[c1a1o1]

FM, H, alignment = match(img1, img2, img_out)

File "E:/百度云同步盘/tongbu/上课/9Python操作电子邮件/9.2发送邮件/9.2.1SMTP发送邮件/pin7.py", line 54, in match
FM, fm_match = fundEst(pts1, pts2, good)
File "E:/百度云同步盘/tongbu/上课/9Python操作电子邮件/9.2发送邮件/9.2.1SMTP发送邮件/pin7.py", line 16, in fundEst
fm_match = good[mask.ravel() == 1]
AttributeError: 'NoneType' object has no attribute 'ravel'