MacBook Air Early 2015 SSD > MacBook Pro Early 2013?
Have you tried reverting to the original macOS that was shipped with this system? If you can reproduce the same behavior with Mavericks/Yosemite then you could very well confirm that this behavior is rooted in an SSD failure vs file system issue. 

This blog post lists a number of issues as to why Mojave cannot find your hard disk, I would perform a systematic check before trying to swap out the hard disk.