Add comprehensive test coverage and fix empty branch issue

internal/vault/vault.go

@@ -21,13 +21,16 @@ type Vault struct {
 }
 
 // NewVault creates a new Vault instance
-func NewVault(fs afero.Fs, name string, stateDir string) *Vault {
-	return &Vault{
+func NewVault(fs afero.Fs, stateDir string, name string) *Vault {
+	secret.Debug("Creating NewVault instance")
+	v := &Vault{
 		Name:        name,
 		fs:          fs,
 		stateDir:    stateDir,
 		longTermKey: nil,
 	}
+	secret.Debug("Created NewVault instance successfully")
+	return v
 }
 
 // Locked returns true if the vault doesn't have a long-term key in memory