Ignore receipts pointing at missing or invalid events (#3817)
* Ignore receipts pointing at missing or invalid events
* Remove extra whitespace from log message
* Unit tests for ignoring invalid receipts
* Improve comments around getEventReadUpTo
* Re-instate second param to compareEventOrdering in test
Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>
* Further improve comments around getEventReadUpTo
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Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>