all: Minor cleanups

if x { return true } return false => return x

	fmt.Sprintf("%v", x) => fmt.Sprint(x) or x.String()

The fmt.Sprintf idiom is still used in the SecretString tests, where it
serves security hardening.

internal/archiver/testing_test.go

@@ -217,7 +217,7 @@ func TestTestWalkFiles(t *testing.T) {
 					return err
 				}
 
-				got[p] = fmt.Sprintf("%v", item)
+				got[p] = fmt.Sprint(item)
 				return nil
 			})