I couldn't figure out a direct solution within Factorio, but rebooting my whole computer solved the issue and I can open the game again. Hopefully my log file will help in some way of finding the cause.

Was playing this morning. Saved a game and when I try to come back later, the app crashes whenever I try to open it. Anyone know how to fix this?

Message asked to post the log here on the forum. Here is the current log:

0.000 2015-05-21 10:20:36; Factorio 0.11.22 (Build 14011, mac)
0.000 ...