How about some crash from Couchbaselite SDK iOS

Mobile Couchbase Lite
1

I work with couchbaselite on iOS,
I received 4 crash report from my crash system. It occurs sometime.
See it in the picture below:

Screen Shot 2016-01-14 at 11.39.38.png732×2278 217 KB

What is these crash affect?
Can I fixed it? How?

Thank you!