fix(grpc): ensure connection errors show onscreen
fix(grpc): ensure connection errors show onscreen

Fix an issue that was preventing grpc connection errors from showing
after a failed connection to a remote node.

Re-throw the error from `startLightningWallet` after logging it so that
it can be handled properly afterwards.

LN-Zap/zap-desktop,LN-Zap/zap-desktop,LN-Zap/zap-desktop