Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'no result or error in response: about google-api-objectivec-client HOT 4 OPEN

What app does this refer to?  What line of code is crashing?

Its crashing in GTLService class at " GTL_DEBUG_ASSERT(errorJSON != nil, @"no 
result or error in response:\n%@",jsonWrapper);"

When i commented this line, it wasn't crashing but when i try to fetch or 
Add/update/delete any task it gives me error " Failed to add task:Error 
Domain=com.google.GTLJSONRPCErrorDomain Code=0 "The operation couldn’t be 
completed. (com.google.GTLJSONRPCErrorDomain error 0.)" UserInfo=0x55bd3d0 
{GTLStructuredError=GTLErrorObject 0x55bd280: {}}"

The same code works fine for iOS 5,But when i rum my project in smulator4.3 it 
gives me the error.

For iOS 4 compatibility, be sure your app includes the files from the project's 
Source/JSON directory.

I already have that folder in my project directory, When i include those files 
in app it gives me error 

"ld: duplicate symbol _SBJSONErrorDomain in 
/Users/saquibe/Library/Developer/Xcode/DerivedData/MobileSyncPro-bgevutwmtttxoah
fvnrdydqbdndw/Build/Products/Debug-iphonesimulator/libGTLTouchStaticLib.a(SBJSON
.o) and 
/Users/saquibe/Library/Developer/Xcode/DerivedData/MobileSyncPro-bgevutwmtttxoah
fvnrdydqbdndw/Build/Intermediates/MobileSyncPro.build/Debug-iphonesimulator/Mobi
leSyncPro.build/Objects-normal/i386/SBJSON.o for architecture i386
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang 
failed with exit code 1"