Income Taxes (Details) - Schedule of Deferred Tax Assets and Liabilities - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020
Deferred tax assets:
Employee benefits	$ 4,789	$ 4,794
Inventory	1,946	1,904
Accounts receivable	119	207
Tax credits	2,027	1,610
Other assets	883	1,073
Lease Liability	2,593	2,807
Capital Loss carry-forward	2,602	2,515
Net operating loss carryforwards	6,203	6,185
Total deferred tax asset	21,162	21,095
Deferred tax liabilities:
Property, plant and equipment	(666)	(1,518)
Right of use asset	(2,514)	(2,696)
Other liabilities	(195)	(193)
Deferred state income tax	(932)	(842)
Net deferred tax asset	16,855	15,846
Valuation allowance	(16,863)	(15,854)
Net deferred tax (liability) asset	$ (8)	$ (8)