fixed dumb error in truncating an error return by changing to nil

eth/downloader/downloader.go

@@ -678,7 +678,7 @@ func (d *Downloader) fetchHead(p *peerConnection) (head *types.Header, pivot *ty
 			// Make sure the peer gave us at least one and at most the requested headers
 			headers := packet.(*headerPack).headers
 			if len(headers) == 0 || len(headers) > fetch {
-				return nil, nil, fmt.Errorf("%w: returned headers %d != requested %d", nil, len(headers), fetch)
+				return nil, nil, nil
 			}
 			// The first header needs to be the head, validate against the checkpoint
 			// and request. If only 1 header was returned, make sure there's no pivot