Significant accounting policies - Summary of Useful Lives of Plant and Equipment (Details)	12 Months Ended
	Oct. 31, 2021
Computers
Disclosure of detailed information about property, plant and equipment [line items]
Useful life of plant and equipment	3 years
Vehicles
Disclosure of detailed information about property, plant and equipment [line items]
Useful life of plant and equipment	5 years
Plant equipment
Disclosure of detailed information about property, plant and equipment [line items]
Useful life of plant and equipment	5 years
Storage containers
Disclosure of detailed information about property, plant and equipment [line items]
Useful life of plant and equipment	10 years