fix(p2p): dag MissingManifest sigfaults if there is a nil manifest

guard against a nil manifest & return an error

cmd/print.go

@@ -245,7 +245,7 @@ func PrintProgressBarsOnEvents(w io.Writer, bus event.Bus) {
 	progress := map[string]*mpb.Bar{}
 
 	if bus == nil {
-		log.Errorf("event bus is nil")
+		log.Debugf("event bus is nil")
 		return
 	}
 	// wire up a subscription to print download progress to streams

p2p/dag.go

@@ -29,6 +29,9 @@ func (node *QriNode) NewManifest(ctx context.Context, path string) (*dag.Manifes
 // MissingManifest returns a manifest describing blocks that are not in this
 // node for a given manifest
 func (node *QriNode) MissingManifest(ctx context.Context, m *dag.Manifest) (missing *dag.Manifest, err error) {
+	if m == nil {
+		return nil, fmt.Errorf("nil manifest")
+	}
 	ng, err := newNodeGetter(node)
 	if err != nil {
 		return nil, err