add VoidWallet and make it the default.

lnbits/settings.py

@@ -3,7 +3,7 @@ import os
 
 
 wallets_module = importlib.import_module("lnbits.wallets")
-wallet_class = getattr(wallets_module, os.getenv("LNBITS_BACKEND_WALLET_CLASS", "LntxbotWallet"))
+wallet_class = getattr(wallets_module, os.getenv("LNBITS_BACKEND_WALLET_CLASS", "VoidWallet"))
 
 LNBITS_PATH = os.path.dirname(os.path.realpath(__file__))
 LNBITS_DATA_FOLDER = os.getenv("LNBITS_DATA_FOLDER", os.path.join(LNBITS_PATH, "data"))

lnbits/wallets/__init__.py

@@ -1,5 +1,6 @@
 # flake8: noqa
 
+from .void import VoidWallet
 from .clightning import CLightningWallet
 from .lndgrpc import LndWallet
 from .lntxbot import LntxbotWallet

lnbits/wallets/void.py

@@ -0,0 +1,19 @@
+from typing import Optional
+
+from .base import InvoiceResponse, PaymentResponse, PaymentStatus, Wallet, Unsupported
+
+
+class VoidWallet(Wallet):
+    def create_invoice(
+        self, amount: int, memo: Optional[str] = None, description_hash: Optional[bytes] = None
+    ) -> InvoiceResponse:
+        raise Unsupported("")
+
+    def pay_invoice(self, bolt11: str) -> PaymentResponse:
+        raise Unsupported("")
+
+    def get_invoice_status(self, checking_id: str) -> PaymentStatus:
+        raise Unsupported("")
+
+    def get_payment_status(self, checking_id: str) -> PaymentStatus:
+        raise Unsupported("")