Fix origin migrator for SSO logins

[dbkr]

For some reason this was trying to close the same window twice
when the app was reloaded after an SSO login. Possibly also a
problem on electron < 6 - presumably a race condition.

Merging to release branch

[jryans]

Hmm, why would the events come back multiple times...? Seems suspicious right?

[dbkr]

Well, the events coming back is legit since with SSO we are coming back to the page and therefore loading up the app again, causing another origin migration attempt. In this case the old listeners will still be there.

[jryans]

Hmm, I see... What about the case of getting origin_migration_complete one time followed by origin_migration_nodata the next? Is that possible?

Effectively I am wondering if we need to remove all listeners whenever any one of them fires.

[dbkr]

Yeah, we technically do, although in practice nobody should actually need the migrator now so there's practically zero chance of actually hitting that case. That said, I guess if we're fixing it we should fix it properly.

[jryans]

Thanks, looks good! 😁