Assertion Error

[EgorusAbobus434]

Warning (from warnings module):
File "C:\Users\user\Desktop\landfall-master\process_data.py", line 13
import shapely.geos
DeprecationWarning: The 'shapely.geos' module is deprecated, and will be removed in a future version. All attributes of 'shapely.geos' are available directly from the top-level 'shapely' namespace (since shapely 2.0.0).
Reusing existing coastline data
Extracting coastline data...
Traceback (most recent call last):
File "C:\Users\user\Desktop\landfall-master\process_data.py", line 485, in
process(options)
File "C:\Users\user\Desktop\landfall-master\process_data.py", line 429, in process
shp_to_csv(find_with_ext(coast_dir, 'shp'), coast_csv)
File "C:\Users\user\Desktop\landfall-master\process_data.py", line 376, in find_with_ext
assert len(matches) == 1
AssertionError

What happened and how do I fix it?