Github user jbaker-nca commented on the issue:
https://github.com/apache/tinkerpop/pull/818
Hi @spmallette, I've made the changes requested.
My understanding is that in some cases, when removing nodes and/or edges,
the collection of edges on a vertex can end up containing null values (I
believe they should be properly removed rather than replaced with nulls, but my
knowledge of the Tinkerpop codebase is very limited so I wasn't sure why this
would be happening). These null values were causing issues when looping across
the collection, which was resulting in the exception thrown.
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