E_NOTICE on contribution confirm page

[demeritcowboy]

Overview

The receipt_from_email value ended up missing the ?? NULL when it was recently converted from Array::value.

[civibot]

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[eileenmcnaughton]

ok without test - it would be possible to add a test on this one but we also acknowledge they are a bit more optional when fixing a regression as fixing is a bit less optional

[demeritcowboy]

Thanks!