Income Taxes - Summary of Reconciliation of Provision from Income Taxes from Operations (Details) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Income Tax Disclosure [Abstract]
Federal income taxes expected at the statutory rate	$ 5,101	$ (22,649)	$ (1,845)
State income taxes, less federal income tax benefit	586	(1,117)	222
Stock compensation	(83)	86	321
Business meals and entertainment	130	18	37
Research and development tax credit	(288)	(199)	(218)
Goodwill impairment		11,741	2,183
Other	441	467	3
Federal tax rate change on deferred taxes			31
Total income tax expense/(benefit)	$ 5,887	$ (11,653)	$ 734

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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