Fix groups proposal error

[nullpointer0x00]

Description

There was a filtering of transactions that were not from the groups module and it would lose the index of the required event log index. Fixed by returning a tuple with the expected index.

closes: #499

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[nullpointer0x00]

I deployed this fix to testnet and re-ran a total of 1022 blocks worth of transaction processing. This fixed them all.

Here is a link from the #499 example error at block: 18607185 https://explorer.test.provenance.io/block/18607185