Antonyms for the phrase "has a crack" would include, but are not limited to, an array of positive phrases. Some might describe an object as being "flawless," "perfect," or even "immaculate." Related antonyms could involve the idea of being "unbroken," "undamaged," or "whole." These descriptors help to provide a sense of positive contrast to the negative connotations associated with having a crack. Additionally, the use of antonymic phrases can help to provide context for the severity of the issue, as well as frame it in a more optimistic light.