Investigating a realm sync fuzzer failure (REALMC-10073), discovered that this is likely an issue with the core binary.

This occurs when issuing the following (see the attached json file for a minimal reproduction with the realm sync fuzzer)

1. CreateObject
2. ArrayInsert of a null link
3. EraseObject

steps 1+2 together work fine, and steps 1+3 alone work as well. However, all 3 together cause the following error:
libc++abi.dylib: terminating with uncaught exception of type realm::KeyNotFound: No object with key '-2' in 'class_jl'
 

Please let me know if there's any other information I can provide