player:get_properties() may return nothing inside on_joinplayer

[appgurueu]

Minetest version

5.5

Summary

See this bug report. The line in question contains just local mesh = player:get_properties().mesh and sometimes triggers an "attempt to index a nil value" error when called from inside on joinplayer.

Steps to reproduce

minetest.register_on_joinplayer(function(player) local _ = player:get_properties().something end)

this seems to be a Heisenbug so you may have to try various connection scenarios which may invalidate the player (properties)

Possible fixes

1. Code-wise: Returning an empty table (may lead to follow-up errors as some properties may be assumed to be non-nil)
2. Documentation-wise: Document when get_properties() returns nothing (currently the docs claim it returns an object property table, which is not always the case), which seems to be the case (1) if the objref is invalid (player left?) or (2) if m_prop is null (how is this even possible?)

[SmallJoker]

Does #12189 help in this regard?

[appgurueu]

It may, but I can't say for sure. How would I trigger such an invalid objref inside on_joinplayer? The crash in character_anim doesn't involve get_connected_players BTW...

[sfan5]

Without a reliable reproducer this doesn't seem fixable...

[Zughy]

I've run a devtest world 15 times and a MTG world 10 times, trying to perform different actions: no crash experienced. I invite to open another issue when more information will be available to trigger this crash (if still exists). Closing here