Better Debug Logging & Null Byte Bug Fix

[bh2smith]

This PR accomplishes two things:

1. Adding relevant context to Debug logging (pointing to the specific offending event) on store_event error:

So before we were seeing: Error: store_event while now we see

 Error: store_event Log { event: "erc1155_uri", block_number: 15275205, log_index: 137, transaction_index: 46, address: Address(0x495f947276749Ce646f68AC8c248420045cb7b5e), fields: [String("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\u{1}\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"), Uint(Uint(BitWidth(256), 85244680541858928040054182450164838257542484891320981406559063124705063993345))] }

which uniquely identifies the offending Log.

2. Replaces trim null bytes with replace null bytes (so we don't miss internal null bytes - like in the updated test example).

   Test Plan

Altered test now passes.

[bh2smith]

I have tested this on the offending event log. Will merge and deploy.