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Other Current Assets - Schedule of Other Current Assets (Details) - USD ($) $ in Thousands | Jan. 31, 2021 | Apr. 30, 2020
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Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] |  |
Deposits | $ 126 | $ 60
Other receivables | 244 | 2
Prepaid insurance | 411 | 124
Prepaid offering costs | 56 | 275
Prepaid expenses- other | 164 | 127
Other current assets | $ 1,001 | $ 588

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