Bug

[kjz1997]

hello, doctor
There seems to be a bug in the latlon_2-SAR_coord function in prep_slc_data when looping to determine the range of the mask, n_iter=1 not accumulated
`n_iter = 1

while mask.nonzero()[0].shape[0] == 0 and  n_iter<10: 
    print('It seems that you AOI is outside of Topstack region')
    print('We will modify your AOI...')
    dist += 0.001
    lat_mask = np.abs(lat_data-lat_p) < dist
    lon_mask = np.abs(lon_data-lon_p) < dist
    mask = lat_mask*lon_mask`