Hey there. Hope you're still around, Eric. I have been plagued with the same problem. Happens most often when I am using a plug-in. Here's the log. Thx ahead of time for the help, if you get this!
3/1/15 12:05:55.327 PM Logic Pro X[454]: Exception caught: *** setObjectForKey: key cannot be nil
Stack trace: (
0 CoreFoundation 0x00007fff8f3ae66c __exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff8d5d476e objc_exception_throw + 43
2 CoreFoundation 0x00007fff8f296876 -[__NSDictionaryM setObject:forKey:] + 1174
3 Logic Pro X 0x00000001085a9323 _ZNSt6vectorIPP6DDESCRSaIS2_EE13_M_insert_auxEN9__gnu_cxx17__normal_iteratorIPS 2_S4_EERKS2_ + 50067
4 Logic Pro X 0x00000001085757d4 _ZNSt6vectorI11TOSCServiceSaIS0_EE13_M_insert_auxEN9__gnu_cxx17__normal_iterato rIPS0_S2_EERKS0_ + 26612
5 Logic Pro X 0x000000010860eecd _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 369261
6 Logic Pro X 0x00000001085d6b9e _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 139070
7 AppKit 0x00007fff8900e839 __68-[NSDocument(NSDeprecated) saveToURL:ofType:forSaveOperation:error:]_block_invoke_2 + 149
8 AppKit 0x00007fff8900e76f __68-[NSDocument(NSDeprecated) saveToURL:ofType:forSaveOperation:error:]_block_invoke + 222
9 Foundation 0x00007fff874741bb -[NSFileCoordinator _invokeAccessor:thenCompletionHandler:] + 255
10 Foundation 0x00007fff875f80c3 __98-[NSFileCoordinator coordinateReadingItemAtURL:options:writingItemAtURL:options:error:byAccessor:]_ block_invoke + 135
11 Foundation 0x00007fff875fa974 __110-[NSFileCoordinator(NSPrivate) _coordinateReadingItemAtURL:options:writingItemAtURL:options:error:byAccessor:] _block_invoke428 + 301
12 Foundation 0x00007fff875f9599 -[NSFileCoordinator(NSPrivate) _invokeAccessor:orDont:andRelinquishAccessClaim:] + 351
13 Foundation 0x00007fff875fa567 -[NSFileCoordinator(NSPrivate) _coordinateReadingItemAtURL:options:writingItemAtURL:options:error:byAccessor:] + 944
14 Foundation 0x00007fff875f802d -[NSFileCoordinator coordinateReadingItemAtURL:options:writingItemAtURL:options:error:byAccessor:] + 146
15 AppKit 0x00007fff88fdef0a -[NSDocument _coordinateReadingContentsAndWritingItemAtURL:error:byAccessor:] + 222
16 AppKit 0x00007fff8900e64b -[NSDocument(NSDeprecated) saveToURL:ofType:forSaveOperation:error:] + 339
17 Logic Pro X 0x00000001085d97ec _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 150412
18 AppKit 0x00007fff88fe21a4 __66-[NSDocument saveToURL:ofType:forSaveOperation:completionHandler:]_block_invoke + 550
19 AppKit 0x00007fff88fce6a9 -[NSDocument continueFileAccessUsingBlock:] + 222
20 AppKit 0x00007fff88fcebfd -[NSDocument _performFileAccessOnMainThread:usingBlock:] + 762
21 AppKit 0x00007fff88fcf8f7 -[NSDocument performAsynchronousFileAccessUsingBlock:] + 484
22 AppKit 0x00007fff88fe1f6f -[NSDocument saveToURL:ofType:forSaveOperation:completionHandler:] + 148
23 AppKit 0x00007fff88fddc6f __85-[NSDocument saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:]_block_ invoke_2 + 296
24 AppKit 0x00007fff8900d3fa -[NSDocument _commitEditingThenContinue:] + 495
25 AppKit 0x00007fff8900d5ad -[NSDocument _commitEditingWithDelegate:didSomethingSelector:contextInfo:thenContinue:] + 138
26 AppKit 0x00007fff88fddb35 __85-[NSDocument saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:]_block_ invoke + 510
27 AppKit 0x00007fff88fcd902 -[NSDocument performActivityWithSynchronousWaiting:usingBlock:cancellationHandler:] + 61
28 AppKit 0x00007fff88fdd928 -[NSDocument saveToURL:ofType:forSaveOperation:delegate:didSaveSelector:contextInfo:] + 169
29 AppKit 0x00007fff88fd96bb __67-[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:]_block_invoke_31449 + 213
30 AppKit 0x00007fff88fcdcda -[NSDocument continueActivityUsingBlock:] + 323
31 AppKit 0x00007fff88fd95d9 __67-[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:]_block_invoke_21446 + 265
32 AppKit 0x00007fff88fd8a8c -[NSDocument _checkForFileChangesThenSave:saveAs:orCancel:] + 691
33 AppKit 0x00007fff88fd94c0 __67-[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:]_block_invoke1443 + 503
34 AppKit 0x00007fff89005672 -[NSDocument _checkAutosavingIgnoringSafetyChecksThenContinue:] + 119
35 AppKit 0x00007fff88fd8ea5 __67-[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:]_block_invoke_2 + 498
36 AppKit 0x00007fff8900d3fa -[NSDocument _commitEditingThenContinue:] + 495
37 AppKit 0x00007fff8900d5ad -[NSDocument _commitEditingWithDelegate:didSomethingSelector:contextInfo:thenContinue:] + 138
38 AppKit 0x00007fff88fd8ca4 __67-[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:]_block_invoke + 353
39 AppKit 0x00007fff88fcd902 -[NSDocument performActivityWithSynchronousWaiting:usingBlock:cancellationHandler:] + 61
40 AppKit 0x00007fff88fd8b36 -[NSDocument saveDocumentWithDelegate:didSaveSelector:contextInfo:] + 128
41 Logic Pro X 0x00000001085d5d12 _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 135346
42 libsystem_trace.dylib 0x00007fff88090cd7 _os_activity_initiate + 75
43 AppKit 0x00007fff88d87b71 -[NSApplication sendAction:to:from:] + 452
44 MAToolKit 0x000000010be0a348 _Z28CreateColorRefWithComponentsffff + 21064
45 Logic Pro X 0x00000001085d290f _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 122031
46 Logic Pro X 0x0000000108607add _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 339581
47 Logic Pro X 0x000000010860ca4a _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 359914
48 Logic Pro X 0x000000010860c9db _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 359803
49 AppKit 0x00007fff88bac608 -[NSApplication run] + 711
50 AppKit 0x00007fff88b97a14 NSApplicationMain + 1832
51 Logic Pro X 0x00000001085d2bf5 _ZNSt6vectorI5CTRowSaIS0_EEaSERKS2_ + 122773
52 libdyld.dylib 0x00007fff836ea5c9 start + 1
)
3/1/15 12:05:55.757 PM Logic Pro X[454]: *** setObjectForKey: key cannot be nil
3/1/15 12:05:55.774 PM com.apple.xpc.launchd[1]: (com.apple.ReportCrash[563]) Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.ReportCrash
3/1/15 12:05:56.000 PM kernel[0]: Sandbox: mdworker(565) deny file-read-data /Applications/GarageBand.app/Contents/Frameworks/MACore.framework/Versions/A/MA Core