[ERROR]: Failed to decrypt OMEMO message - OmemoHelper is null

[o---]

Bevor you create a new issue:

- [X] I searched for similar issues and did not find one
- [X] I'm using the latest version available in the [Windows Store](https://www.microsoft.com/store/apps/9NW16X9JB5WV)

I'm submitting a...:

• Bug report (I searched for similar issues and did not find one)

• Question or Support request

Current behavior:

I am not sure how to get OMEMO working. I have exchanged a bunch of messages (unencrypted), but as soon as switch on encryption, I am not able to send nor receive messages nor message carbons.

I am finding following messages in the log:

[ERROR][27.05.2020 22:15:28]: Failed to decrypt OMEMO message - OmemoHelper is null 
[ERROR][27.05.2020 22:15:51]: Failed to send OMEMO message - OmemoHelper is null 
[ERROR][27.05.2020 22:16:58]: Failed to send OMEMO message - OmemoHelper is null 
[ERROR][27.05.2020 22:17:36]: Failed to decrypt OMEMO message - OmemoHelper is null 
[ERROR][27.05.2020 22:17:41]: Failed to send OMEMO message - OmemoHelper is null 
[ERROR][27.05.2020 22:18:50]: Failed to load OMEMO prekeys for: [email protected] 

I have checked if I see any un-trusted OMEMO keys, but all are set to trusted.

Expected behavior:

OMEMO messages are working. No errors in the log.

Minimal reproduction of the problem with instructions:

1. Enable OMEMO
2. Exchange some messages

Environment:

App Version(s): 
v.0.26.2.0 <!-- Which version of the App are you using (e.g. v.0.2.0) -->

Windows 10 Version Number: <!-- https://en.wikipedia.org/wiki/Windows_10_version_history -->
- [X] 1909
- [ ] 1809
- [ ] 1803
- [ ] 1709
- [ ] 1703
- [ ] 1607
- [ ] 1511
- [ ] 1507
- [ ] Insider Build (build number: )
- [ ] Misc:

Device form factor:
- [X] Desktop
- [ ] Mobile
- [ ] Xbox
- [ ] Surface Hub

Where did you got the APP from?
- [X] [Windows Store](https://www.microsoft.com/store/apps/9NW16X9JB5WV)
- [ ] Self-build, using a provided release source
- [ ] Self-build, repo cloned at [dd.mm.yyy] <!-- When did you clone the repo! -->
- [ ] Misc, got it from... <!-- Please tell us your source! -->

[COM8]

This looks to me like the way OMEMO keys are being stored is still very much broken...
I need to refactor this.

[o---]

I guess these are also related to this topic:

[ERROR][29.05.2020 00:28:21]: OmemoStore: No such signed pre key: 5 
[ERROR][29.05.2020 00:28:21]: Failed to load OMEMO signed prekey pair for: [email protected] 
[ERROR][29.05.2020 00:28:21]: OmemoStore: No such signed pre key: 5 
[ERROR][29.05.2020 00:28:21]: Failed to load OMEMO signed prekey pair for: [email protected] 

[COM8]

Yes. This is definitely caused by UWPX loosing keys...

[COM8]

Fixed by #146.