Broken payment validation

[Kincaid O'Neil]

Since all of the methods within https://github.com/machinomy/machinomy/blob/master/packages/machinomy/src/PaymentValidation.ts are async and return promises, the conditions can't be applied to && directly. In effect, the isValid method just returns the last boolean promise (isAboveMinSettlementPeriod), and never checks any of the other conditions.

This is the cause for #231, as when passing Machinomy a payment with a negative price, it would log the error that the payment was invalid/price was negative, but isValid here

machinomy/packages/machinomy/src/ChannelManager.ts

Line 109 in 7009e84

 const valid = await this.paymentManager.isValid(payment, channel) 

would still always return true, saving the payment to the DB. Then when attempting to claim it, it cleared the entire channel, since the value is parsed as an unsigned integer.

[Sergey Ukustov]

🤦‍♂️

Thank you @kincaidoneil!!

[Sergey Ukustov]

Fixed in #233