Fix peer dropping (#2780)

It turns out that we drop connection if we fail to process a message
because of chain/store/internal error, eg we have a header already, so
we refuse it and drop the peer.
This pr doesn't forward this error to the peer error channel so the
connection will not be dropped.

p2p/src/conn.rs

@@ -51,6 +51,10 @@ macro_rules! try_break {
 		match $inner {
 			Ok(v) => Some(v),
 			Err(Error::Connection(ref e)) if e.kind() == io::ErrorKind::WouldBlock => None,
+			Err(Error::Store(_))
+			| Err(Error::Chain(_))
+			| Err(Error::Internal)
+			| Err(Error::NoDandelionRelay) => None,
 			Err(e) => {
 				let _ = $chan.send(e);
 				break;

p2p/src/peer.rs

@@ -61,7 +61,7 @@ macro_rules! connection {
 	($holder:expr) => {
 		match $holder.connection.as_ref() {
 			Some(conn) => conn.lock(),
-			None => return Err(Error::Internal),
+			None => return Err(Error::ConnectionClose),
 			}
 	};
 }