mod_rest: Catch and log errors in callback promise chain From the code it looks like it should be possible to reply to an error stanza, but it did not. Turns out I was saved by my local developer mode module which throws errors if an attempt is made to create an errror reply to an error stanza. However nothing collects this error from the promise, so all I got was confusion.

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summary: Remote Roster Management
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Introduction
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This module adds support for [XEP-0321: Remote Roster Management] which
is commonly used to allow components such as transports to modify the
rosters of local users.