Remove Duplicate Primary OCRs Error

Hello,

We ended up with quite a lot of duplicate OCRs (more than we can actually do manually), so I was trying to use the bulk data process to help merge these. I continue to receive a Batch Apex Error with a full message of:

"First error: Attempt to de-reference a null object"

I have been searching previously asked questions and seem to see this referenced a lot with customizable rollups, but did not see anything related to this type of job.

Any help would be greatly appreciated! Thanks!