Non-throwing counterpart of resolveSendAmount, for availability
checks that must not reject the router: returns the positive-integer sats
from the explicit amount or the BIP21 amount= param, or undefined when
none is present or the value is not a positive integer. The missing-vs-invalid
distinction is left to resolveSendAmount at quote time.
Non-throwing counterpart of resolveSendAmount, for availability checks that must not reject the router: returns the positive-integer sats from the explicit
amountor the BIP21amount=param, orundefinedwhen none is present or the value is not a positive integer. The missing-vs-invalid distinction is left toresolveSendAmountat quote time.