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I believe you are getting this error because of the way your bounding box input is defined. For bounding box entries, BRAILS expects the location parameter defined as a tuple in the format location=(lon1,lat1,lon2,lat2). Here the longitude and latitude values are the coordinates of the opposite vertices of a rectangular bounding box (at the moment, BRAILS only takes rectangular bounding box input).
For instance, one can get a random set of 100 buildings contained in the West Los Angeles bounding shown in the attachment by defining the bounding box based on the coordinates of its top left vertex (-118.4546,34.0111) and bottom right vertex (-118.3866,34.0436) via the syntax:
invGenerator = InventoryGenerator(location=(-118.4546,34.0111,-118.3866,34.0436),
nbldgs=100, randomSelection=True,
GoogleAPIKey="YOUR-API-KEY")
I hope this helps! Please let me know if you run into any other issues.