I recently attempted, and temporarily succeeded, in dual-booting Ubuntu and MacOS Mojave on my MacBook Air. After I installed and successfully tested Ubuntu, I tried to use Disk Utility to create a third partition in ExFat to be shared between the two operating systems. After running for a while, Disk Utility quit unexpectedly, but nothing else seemed out of the ordinary. I tested the new partition on MacOS, and it seemed to work fine. However, when I rebooted my Mac while holding Option, the only bootable disk that showed up was Ubuntu. The output of Disks on Ubuntu (attached image) shows me that the main partition (191 GB Unknown) is no longer recognized, the Shared partition I just created is inexplicably recognized as HFS+ instead of ExFAT as intended.
Is there any way for me to restore MacOS without formatting the damaged partition?