This may increase processing latency a bit, particularly with large
attachments, but will ensure that messages are dispatched in the order
they are received.
It would be nice to enforce ordering on only the dispatch step, so that
we could, for example, decrypt the next websocket message while waiting
for an attachment to download, but that will require a more complicated
refactor. Will stick with the quick fix for now and revisit later.
Fixes#342
// FREEBIE
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