Don't try to make a graph with one line (it will fail), and don't mark analysis as failed if graph isn't made for that reason

1 files changed, 2 insertions, 2 deletions

diff --git a/graph.go b/graph.go
index c56ba48..4ca44a7 100644
--- a/graph.go
+++ b/graph.go
@@ -51,8 +51,8 @@ func Graph(confs map[string]*Conf, bookname string, w io.Writer) error {
 }
 
 func GraphOpts(confs map[string]*Conf, bookname string, xaxis string, guidelines bool, w io.Writer) error {
-	if len(confs) == 0 {
-		return errors.New("No valid confidences")
+	if len(confs) < 2 {
+		return errors.New("Not enough valid confidences")
 	}
 
 	// Organise confs to sort them by page