This is not a bug but for general discussion:
Smack supports the inquiry LastActivity support for a contact via
public boolean isLastActivitySupported(Jid jid)
where jid needs to be FullJid. Generally contact last activity info is of use when the contact is offline. However use of the above method when contact is offline return errors as shown below.
2019-08-13 08:40:01.154 32464-715/org.atalk.android D/SMACK: SENT (0):
<iq to='eagle@atalk.org/atalk' id='Q1SPN-131' type='get'>
<query xmlns='http://jabber.org/protocol/disco#info'>
</query>
</iq>
2019-08-13 08:40:01.169 32464-716/org.atalk.android D/SMACK: RECV (0):
<iq xml:lang='en' to='swordfish@atalk.org/atalk' from='eagle@atalk.org/atalk' type='error' id='Q1SPN-131'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
<error code='503' type='cancel'>
<service-unavailable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
<text xml:lang='en' xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
User session not found
</text>
</error>
</iq>
if the contact is offline when a user login, invoke the isLastActivitySupported() method will always throw exception. I am not sure how this method is being used in application actual implementation and when to use this method.