Skip un-grouped PRs if no default is set

Signed-off-by: jolheiser <john.olheiser@gmail.com>

cmd/generate.go

@@ -44,7 +44,7 @@ func runGenerate(_ *cli.Context) error {
 		}
 	}
 	if defaultGroup == "" {
-		defaultGroup = cfg.Groups[len(cfg.Groups)-1].Name
+		fmt.Println("<!-- WARNING - no default group found -->")
 	}
 
 	entries := processPRs(prs, cfg.NameLabels(), defaultGroup, cfg.SkipRegex)
@@ -88,6 +88,9 @@ PRLoop: // labels in Go, let's get old school
 			}
 		}
 		section := processSection(pr, order, defaultGroup)
+		if section == "" {
+			continue
+		}
 		entries[section] = append(entries[section], pr)
 	}
 	return entries