Gnucash 2.4.11/2.4.13 crash on Mac OS X 10.8.4

[Tim LeMaster]

I've been using Gnucash for years on Linux and now on Mac. However I
attempted to start Gnucash 2.4.11 (which I've been running without issue)
and it crashes. I upgraded to 2.4.13 and it also crashes with the same
problem.

Here is the output

Process:         Gnucash-bin [290]
Path:            /Applications/Gnucash.app/Contents/MacOS/Gnucash
Identifier:      org.gnucash.Gnucash
Version:         ???
Code Type:       X86 (Native)
Parent Process:  launchd [137]
User ID:         501

Date/Time:       2013-08-25 14:37:40.180 -0400
OS Version:      Mac OS X 10.8.4 (12E55)
Report Version:  10

Interval Since Last Report:          4880820 sec
Crashes Since Last Report:           46
Per-App Crashes Since Last Report:   23
Anonymous UUID:                      4B45A729-22B1-FD1A-D6C2-3F3DB632C49B

Crashed Thread:  0  Dispatch queue: com.apple.main-thread

Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000

Application Specific Information:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[__NSCFString stringByAppendingString:]: nil argument'

Application Specific Backtrace 1:
0   CoreFoundation                      0x9721de8b __raiseError + 219
1   libobjc.A.dylib                     0x92d4152e objc_exception_throw +
230
2   CoreFoundation                      0x9717d60b +[NSException
raise:format:] + 139
3   Foundation                          0x93eef08c -[NSString
stringByAppendingString:] + 99
4   Gnucash-bin                         0x00014886 main + 310
5   Gnucash-bin                         0x00014716 start + 54
6   ???                                 0x00000002 0x0 + 2

I deleted /Library/Gnucash-2.4 and it was recreated when I relaunch Gnucash.
Any ideas?

Thanks