added exit condition if no modules were parsed

Author: hellt

cmd/export.go

@@ -41,6 +41,9 @@ var exportCmd = &cobra.Command{
 		if err := ms.Read(viper.GetString("module")); err != nil {
 			log.Fatal(err)
 		}
+		if len(ms.Modules) == 0 {
+			log.Fatal("no modules found, exporting from submodules is not yet supported")
+		}
 		var mn string // module name
 		// at this moment ms contains only one module
 		// which was read by the path provided within -m flag