message: Clarify PRF-Based Deriver error text.
diff: @@ -64,11 +64,11 @@ func newPRFBasedDeriver(prfKeyData *tinkpb.KeyData, derivedKeyTemplate *tinkpb.K
  func (p *prfBasedDeriver) DeriveKeyset(salt []byte) (*keyset.Handle, error) {
  randomness, err := p.prf.Compute(salt)
  if err != nil {
  - return nil, fmt.Errorf("compute randomness from PRF: %v", err)
  + return nil, fmt.Errorf("compute randomness from PRF failed: %v", err)
  }
  keyData, err := internalregistry.DeriveKey(p.derivedKeyTemplate, randomness)
  if err != nil {
  - return nil, fmt.Errorf("derive key: %v", err)
  + return nil, fmt.Errorf("derive key failed: %v", err)
  }
  // Fill in placeholder values for key ID, status, and output prefix type.
  // These will be populated with the correct values in the keyset deriver
  