missing campaigns folder prevents mekhq from starting up

[db984]

Environment

Tested 0.45, 0 .46, and 0.47
Tested on Windows and Linux.

Description

If the campaigns folder is not present, mekhq fails to start, (silent exit).
The logs/mekhqlog.txt file contains:

Exception in thread "main" java.lang.NullPointerException
at mekhq.Utilities.lastFileModified(Utilities.java:356)
at mekhq.gui.StartUpGUI.(StartUpGUI.java:44)
at mekhq.MekHQ.startup(MekHQ.java:298)

Background

After several months of creating campaign save files as the campaign progressed; I'd filled the linux vm hd I was using for mekhq. I moved the campaigns folder to another drive to free up some space to install and run some tools to resize the drive. Afterwards I attempted to run mekhq and got the error. I eventually realized that I'd forgotten to copy the campaigns folder back to the folder.

This isn't going to be a common issue, but the software should handle not finding the campaigns folder more gracefully. Simply reporting that it couldn't find the campaigns folder in the log would be an improvement. A better fix would be creating the missing folder.