message: send page: unset fiat amt if nano amt <= 0 or invalid
diff: @@ -158,10 +158,13 @@ export class SendComponent implements OnInit {
  // An update to the Nano amount, sync the fiat value
  syncFiatPrice() {
  - if (!this.validateAmount()) return;
  + if (!this.validateAmount() || Number(this.amount) === 0) {
  + this.amountFiat = null;
  + return;
  + }
  const rawAmount = this.getAmountBaseValue(this.amount || 0).plus(this.amountExtraRaw);
  if (rawAmount.lte(0)) {
  - this.amountFiat = 0;
  + this.amountFiat = null;
  return;
  }
  