AVOSCloudSNS.m crash

[wongkoo]

-[__NSDictionaryM setObject:forKey:]: object cannot be nil (key: username)

-[__NSDictionaryM setObject:forKey:] + 932
__54+[AVOSCloudSNS onSuccess:withToken:andExpires:andUid:]_block_invoke (AVOSCloudSNS.m:0)