feat: use error pragma to signal abstract methods

libp2p/tcptransport.nim

@@ -44,3 +44,5 @@ method dial*(t: TcpTransport, address: MultiAddress): Future[Connection] {.async
   ## dial a peer
   let client: StreamTransport = await connect(address)
   result = await t.connHandler(t.server, client)
+
+method supports(t: Transport, address: MultiAddress): bool = true

libp2p/transport.nim

@@ -33,7 +33,7 @@ method connHandler*(t: Transport,
   t.connections.add(connHolder)
   result = conn
 
-method init*(t: Transport) {.base.} = 
+method init*(t: Transport) {.base, error: "not implemented".} = 
   ## perform protocol initialization
   discard
 
@@ -53,12 +53,12 @@ method listen*(t: Transport, ma: MultiAddress, handler: ConnHandler) {.base, asy
   t.ma = ma
   t.handler = handler
 
-method dial*(t: Transport, address: MultiAddress): Future[Connection] {.base, async.} = 
+method dial*(t: Transport, address: MultiAddress): Future[Connection] {.base, async, error: "not implemented".} = 
   ## dial a peer
   discard
 
-method supports(t: Transport, address: MultiAddress): bool {.base.} = 
+method supports(t: Transport, address: MultiAddress): bool {.base, error: "not implemented".} = 
   ## check if transport supportes the multiaddress
   # TODO: this should implement generic logic that would use the multicodec 
   # declared in the multicodec field and set by each individual transport
-  result = true
+  discard