Lightning: Relax GetInfo constraint for LNDhub connections

The LNDhub-compatible implementation by LNbits does not support the `GetInfo` call for all their funding sources — see lnbits/lnbits#1182. By catching that exception in combination with the `LndHubLightningClient`, we give people the ability to still use their LNbits-based LNDhub as a Lightning node.

Fixes btcpayserver#4482.

BTCPayServer/Payments/Lightning/LightningLikePaymentHandler.cs

@@ -9,6 +9,7 @@
 using BTCPayServer.Data;
 using BTCPayServer.HostedServices;
 using BTCPayServer.Lightning;
+using BTCPayServer.Lightning.LndHub;
 using BTCPayServer.Logging;
 using BTCPayServer.Models;
 using BTCPayServer.Models.InvoicingModels;
@@ -136,6 +137,10 @@ public async Task<NodeInfo[]> GetNodeInfo(LightningSupportedPaymentMethod suppor
                 {
                     throw new PaymentMethodUnavailableException("The lightning node did not reply in a timely manner");
                 }
+                catch (NullReferenceException) when (client is LndHubLightningClient)
+                {   // LNDhub-compatible implementation by LNbits does not support GetInfo, see https://github.com/lnbits/lnbits/issues/1182
+                    return new NodeInfo[] {};
+                }
                 catch (Exception ex)
                 {
                     throw new PaymentMethodUnavailableException($"Error while connecting to the API: {ex.Message}" +