Refactor some importprunedfunds checks with guard clause
Refactor some importprunedfunds checks with guard clause

Credit to jkczyz


Former-commit-id: b557adb765dcb57698f73513adbe2aa0e44f2d28
syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin,syscoin/syscoin2,syscoin/syscoin2