maxScale bug within estimateTissueBoundary function

[herrinca]

Hello, I am giving your workflow a go and came across what I think is a bug.

Currently, if maxScale is set to 0 it will be changed to None at line 61 and on the next tile loop will be caught by the else statement (line 67) which trys to convert what is now None to a float at line 69. This returns a TypeError: float() argument must be a string or a number, not 'NoneType'. Simple fix might be to drop maxScale=None and change line 62 from using_mpl_scatter_density(fig, x['y'], x['x'],maxScale) to using_mpl_scatter_density(fig, x['y'], x['x'],None).

Best,
Chuck