add status() method to wallets to be used in initial check.

lnbits/wallets/void.py

@@ -1,6 +1,6 @@
 from typing import Optional, AsyncGenerator
 
-from .base import InvoiceResponse, PaymentResponse, PaymentStatus, Wallet, Unsupported
+from .base import StatusResponse, InvoiceResponse, PaymentResponse, PaymentStatus, Wallet, Unsupported
 
 
 class VoidWallet(Wallet):
@@ -9,6 +9,12 @@ class VoidWallet(Wallet):
     ) -> InvoiceResponse:
         raise Unsupported("")
 
+    def status(self) -> StatusResponse:
+        return StatusResponse(
+            "This backend does nothing, it is here just as a placeholder, you must configure an actual backend before being able to do anything useful with LNbits.",
+            0,
+        )
+
     def pay_invoice(self, bolt11: str) -> PaymentResponse:
         raise Unsupported("")