When working on client side js it often feels like safari is the modern browser that the most special care is required for. Some of this has to do with not the most recent version but the one one before that (much like the most recent IE was often not reqao, people cursed IE).
Another aspect is OS specificity, MS has made it very easy to debug IE without having windows via VMs they put out specifically for this purpose. Meanwhile there is no amount of money Apple will accept from you to run a mac vm on non Mac hardware. I have fond memories of trying to debug issues with Web Workers in safari via sauce labs.
(disclaimer, I worked with Nolan Lawson on pouchdb and he credits me with coming up with the safari is the new ie phrase)