[Chore] Get rid of RpcNoOperationsRun error

Description

Problem: RpcNoOperationsRun isn't actually required anywhere, but we still have it. Furthermore we still have some code that claims to throw it, but actually can't.

Solution: Remove RpcNoOperationsRun, use NonEmpty strategically to avoid the need to use it.

Related issue(s)

Resolves None, I noticed this off-hand when working on something else more complicated and decided to split it out.

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• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

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  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

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