Replace string placeholder with double-quoted in error strings.

cmd/helm/init.go

@@ -221,7 +221,7 @@ func (i *initCmd) run() error {
 			}
 			return nil
 		default:
-			return fmt.Errorf("unknown output format: %s", i.opts.Output)
+			return fmt.Errorf("unknown output format: %q", i.opts.Output)
 		}
 	}
 	if settings.Debug {

cmd/helm/installer/install.go

@@ -136,7 +136,7 @@ func parseNodeSelectorsInto(labels string, m map[string]string) error {
 		if len(el) == 2 {
 			m[el[0]] = el[1]
 		} else {
-			return fmt.Errorf("invalid nodeSelector label: %s", kv)
+			return fmt.Errorf("invalid nodeSelector label: %q", kv)
 		}
 	}
 	return nil