Income Taxes (Details) - Schedule of Deferred Tax Assets and Liabilities - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Deferred tax assets:
Employee benefits	$ 4,794	$ 5,092
Inventory	1,904	1,649
Accounts receivable	207	204
Tax credits	1,610	1,300
Other assets	1,073	148
Lease Liability	2,807	0
Capital Loss carry-forward	2,515	2,455
Net operating loss carryforwards	6,185	5,556
Total deferred tax asset	21,095	16,404
Deferred tax liabilities:
Property, plant and equipment	(1,518)	(1,344)
Right of use asset	(2,696)
Other liabilities	(193)	(343)
Deferred state income tax	(842)	(767)
Net deferred tax asset	15,846	13,950
Valuation allowance	(15,854)	(13,950)
Net deferred tax (liability) asset	$ (8)	$ 0

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from leasing arrangements.

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