Arduino IDE will not open on Mac OS 10.14.6 Mojave

All of a sudden (I was using IDE 1.8.12 this morning for hours) I cannot get any version of the Arduino IDE to open on Mac OS 10.14.6 Mojave. I installed every version back to 1.8.6, but it crashes on startup. The splash screen comes up, it says "initializing packages", then goes away. Any help, please - anyone here know what's happening?

I solved it. I deleted the folders named "Arduino" and "Arduino15" located at users/Username/library. I then reinstalled 1.8.12 and it created the Arduino15 folder. I assume it had been corrupted.

Interesting! Hope that works thru a restart.
I emailed Arduino support about the 1.8.12 problem, we'll see what happens. Problem has been all over the forum today.