refac: atomic merge, lost-update race, RunPurge cost, duplicated walks

internal/domain/entry/entryDomain.go

@@ -55,12 +55,8 @@ func (e FieldError) Unwrap() error {
 	return e.Cause
 }
 
-func invalidField(key string, rule string) error {
-	return FieldError{Key: key, Rule: rule, Cause: ErrInvalidEntry}
-}
-
 func InvalidField(key string, rule string) error {
-	return invalidField(key, rule)
+	return FieldError{Key: key, Rule: rule, Cause: ErrInvalidEntry}
 }
 
 func UniqueViolation(key string) error {