biomemap is nil on generating caverealm (subterrane fork) only with mg

[Poikilos]

I am using experimental mapgen (mg). I'm not sure if this is an mg issue, caverealms issue, or subterrane issue--I looked at the line in question, which uses biomemap, a local variable which should contain the result of minetest.get_mapgen_object("biomemap"). I don't know enough to know why get_mapgen_object would ever return nil after looking up its meaning. If I restart the server, it works for a while, but when trying to dig deeper in a certain location the server crashes. Apparently the problem happens when a caverealm generates.

Seed: BagEnd
Location: /teleport 17,-566,98 (then start digging down)
MapGen: v7
minetest version: 0.5.0-dev (~2018-02-21)
mapgen mods:

• mg
• subterrane
• caverealms (FaceDeer's fork of caverealms which is integrated with mapgen v7's perlin noise and uses subterrane)
• magma_conduits
• minor mapgen mods: moreores, techic, ... for others see https://github.com/expertmm/EnlivenMinetest/blob/master/etc/game-install-ENLIVEN

2018-02-23 19:37:29: ACTION[Main]: [playereffects] Server shuts down. Rescuing data into playereffects.mt
2018-02-23 19:37:29: ACTION[Main]: [playereffects] Wrote playereffects data into /home/owner/.minetest/worlds/FCAWorldB/playereffects.mt.
2018-02-23 19:37:30: ACTION[Main]: [fishing] Server shuts down. saving trophies table
2018-02-23 19:37:31: ERROR[Main]: ServerError: AsyncErr: Lua: finishGenRuntime error from mod 'caverealms' in callback environment_OnGenerated(): ...al/share/minetest/games/ENLIVEN/mods/subterrane/init.lua:181: attempt to index local 'biomemap' (a nil value)
2018-02-23 19:37:31: ERROR[Main]: stack traceback:
2018-02-23 19:37:31: ERROR[Main]: ...al/share/minetest/games/ENLIVEN/mods/subterrane/init.lua:181: in function <...al/share/minetest/games/ENLIVEN/mods/subterrane/init.lua:116>
2018-02-23 19:37:31: ERROR[Main]: /usr/local/share/minetest/builtin/game/register.lua:420: in function </usr/local/share/minetest/builtin/game/register.lua:400>

Without mg installed, at least one caverealm generates without issues (same seed as above, but new world with no mg):
/teleport -25,-971,121
Since it only happens with mg installed, I moved this issue from FaceDeer/minetest-caverealms#2

[Poikilos]

I closed the issue at caverealms since the remaining issue seems to be with mg (correct me if I'm wrong).

[Ekdohibs]

I think the issue is with caverealm, since I think biomemap is not defined if the mapgen used does not support it. Since mg uses the "singlenode" mapgen, biomemap is not supported in it.

[Poikilos]

Thanks, I'll check back in over there.

[Poikilos]

If possible, I could use some more info to help the maintainers fix caverealms or subterrane:
I understand now that mg uses the singlenode mapgen. However:

• Does mg populate minetest.registered_biomes?
• Is there some way to get mg's biome name or ground node (such as "default:dirt_with_grass") at given x,y,z location or a location on the x-z ground plane (so subterrane can decorate "native" caves according to mg's ground as opposed to crashing or leaving out biome-specific decorations)?
  I'll check in at the forum if there is not a simple answer.

[Ekdohibs]

mg does not populate minetest.registered_biomes, and even completely ignores it if you fill it. Getting the ground node at a point is not easy, unfortunately -- I think the best to do is to use mg's get_biome_table and get_nearest_biome functions, as done in the code.

[Poikilos]

ok thanks