Can't add to index - taskWindowWillDisplayError unrecognized selector sent to instance

All of a sudden, I cannot add files to the index in a specific repository. When I do, Console shows lots of errors:

6/4/14 7:33:19.468 AM SourceTree[72161]: CoreData: Error: Unable to dynamically link Librarian.framework
6/4/14 7:33:19.622 AM SourceTree[72161]: BUG in libdispatch client: kevent[EVFILT_WRITE] delete: "No such file or directory" - 0x2
6/4/14 7:33:33.967 AM SourceTree[72161]: -[STGitWindowController taskWindowWillDisplayError:]: unrecognized selector sent to instance 0x4008c5ea0
6/4/14 7:33:33.967 AM SourceTree[72161]: -[STGitWindowController taskWindowWillDisplayError:]: unrecognized selector sent to instance 0x4008c5ea0
6/4/14 7:33:33.968 AM SourceTree[72161]: (
0 CoreFoundation 0x00007fff8c2f525c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff8ea83e75 objc_exception_throw + 43
2 CoreFoundation 0x00007fff8c2f812d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3 CoreFoundation 0x00007fff8c2530f4 __forwarding__ + 452
4 CoreFoundation 0x00007fff8c252ea8 _CF_forwarding_prep_0 + 120
5 SourceTree 0x000000010a86559b SourceTree + 263579
6 CoreFoundation 0x00007fff8c2c3e0c _CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER_ + 12
7 CoreFoundation 0x00007fff8c1b78dd _CFXNotificationPost + 2893
8 Foundation 0x00007fff9343d7ba -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
9 CoreFoundation 0x00007fff8c2c3e0c _CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER_ + 12
10 CoreFoundation 0x00007fff8c1b78dd _CFXNotificationPost + 2893
11 Foundation 0x00007fff9343d7ba -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
12 CoreFoundation 0x00007fff8c22653c _CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK_ + 12
13 CoreFoundation 0x00007fff8c217b95 __CFRunLoopDoBlocks + 341
14 CoreFoundation 0x00007fff8c21791e __CFRunLoopRun + 1982
15 CoreFoundation 0x00007fff8c216f25 CFRunLoopRunSpecific + 309
16 HIToolbox 0x00007fff8bad2a0d RunCurrentEventLoopInMode + 226
17 HIToolbox 0x00007fff8bad27b7 ReceiveNextEventCommon + 479
18 HIToolbox 0x00007fff8bad25bc _BlockUntilNextEventMatchingListInModeWithFilter + 65
19 AppKit 0x00007fff8957726e _DPSNextEvent + 1434
20 AppKit 0x00007fff895768bb -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
21 AppKit 0x00007fff8956a9bc -[NSApplication run] + 553
22 AppKit 0x00007fff895557a3 NSApplicationMain + 940
23 SourceTree 0x000000010a826c14 SourceTree + 7188
)

Quitting and relaunching doesn't help. Other repositories work, just this one is stuck. Any other info I should include? I'm not sure what is unique about this repo. It's a submodule in another repo.