refactor(privval): reverse conditional + more idiomatic Go code with …

…early returns (cometbft#2156)

This change applies the refactoring method of reverse conditional and
using early returns for more idiomatic code which makes the code much
more direct and less nested.

Fixes cometbft#2154

privval/file.go

@@ -102,32 +102,40 @@ func (lss *FilePVLastSignState) CheckHRS(height int64, round int32, step int8) (
  return false, fmt.Errorf("height regression. Got %v, last height %v", height, lss.Height)
  }
 
- if lss.Height == height {
- if lss.Round > round {
- return false, fmt.Errorf("round regression at height %v. Got %v, last round %v", height, round, lss.Round)
- }
+ if lss.Height != height {
+ return false, nil
+ }
 
- if lss.Round == round {
- if lss.Step > step {
- return false, fmt.Errorf(
- "step regression at height %v round %v. Got %v, last step %v",
- height,
- round,
- step,
- lss.Step,
- )
- } else if lss.Step == step {
- if lss.SignBytes != nil {
- if lss.Signature == nil {
- panic("pv: Signature is nil but SignBytes is not!")
- }
- return true, nil
- }
- return false, errors.New("no SignBytes found")
- }
- }
+ if lss.Round > round {
+ return false, fmt.Errorf("round regression at height %v. Got %v, last round %v", height, round, lss.Round)
+ }
+
+ if lss.Round != round {
+ return false, nil
+ }
+
+ if lss.Step > step {
+ return false, fmt.Errorf(
+ "step regression at height %v round %v. Got %v, last step %v",
+ height,
+ round,
+ step,
+ lss.Step,
+ )
+ }
+
+ if lss.Step < step {
+ return false, nil
+ }
+
+ if lss.SignBytes == nil {
+ return false, errors.New("no SignBytes found")
+ }
+
+ if lss.Signature == nil {
+ panic("pv: Signature is nil but SignBytes is not!")
  }
- return false, nil
+ return true, nil
 }
 
 // Save persists the FilePvLastSignState to its filePath.