Milo console importer: fix small bug

This is sometimes nil

BUG=

Review-Url: https://codereview.chromium.org/2981373002
diff --git a/milo/common/config.go b/milo/common/config.go
index 6c9dc91..9fbbec2 100644
--- a/milo/common/config.go
+++ b/milo/common/config.go
@@ -343,7 +343,9 @@
 	// Print some stats.
 	processedConsoles := 0
 	for _, cons := range knownProjects {
-		processedConsoles += cons.Len()
+		if cons != nil {
+			processedConsoles += cons.Len()
+		}
 	}
 	logging.Infof(
 		c, "processed %d consoles over %d projects", len(knownProjects), processedConsoles)