bip21: consider amount=0 in bip21 uri invalid

electrum/bip21.py

@@ -61,7 +61,7 @@ def parse_bip21_URI(uri: str) -> dict:
                 amount = Decimal(m.group(1)) * pow(Decimal(10), k)
             else:
                 amount = Decimal(am) * COIN
-            if amount > TOTAL_COIN_SUPPLY_LIMIT_IN_BTC * COIN:
+            if amount > TOTAL_COIN_SUPPLY_LIMIT_IN_BTC * COIN or amount <= 0:
                 raise InvalidBitcoinURI(f"amount is out-of-bounds: {amount!r} BTC")
             out['amount'] = int(amount)
         except Exception as e:
@@ -92,7 +92,7 @@ def parse_bip21_URI(uri: str) -> dict:
         amount_sat = out.get('amount')
         if amount_sat:
             # allow small leeway due to msat precision
-            if abs(amount_sat - int(lnaddr.get_amount_sat())) > 1:
+            if lnaddr.get_amount_msat() is None or abs(amount_sat - int(lnaddr.get_amount_sat())) > 1:
                 raise InvalidBitcoinURI("Inconsistent lightning field in bip21: amount")
         address = out.get('address')
         ln_fallback_addr = lnaddr.get_fallback_address()