PlanetsLib:extend() overwrites property_expression_names set in planet definition

[quanium]

When a planet is registered via PlanetsLib:extend(), any property_expression_names defined in the planet table are lost. After the call, data.raw["planet"]["velora"].map_gen_settings.property_expression_names does not contain the values set before the call.
Steps to reproduce:

Define a planet with custom property_expression_names (e.g. enemy_base_probability)
Register it via PlanetsLib:extend({ velora })
Check data.raw["planet"][name].map_gen_settings.property_expression_names immediately after — values are missing

Expected behavior:
property_expression_names defined in the planet table should be preserved after PlanetsLib:extend()
Actual behavior:
property_expression_names is empty or missing after PlanetsLib:extend()
Workaround:
Manually patch data.raw["planet"][name] after PlanetsLib:extend():
luaPlanetsLib:extend({ velora })
data.raw["planet"]["velora"].map_gen_settings.property_expression_names["enemy_base_probability"] = "velora_enemy_base_probability"
Mod affected: Velora 1.3.1

[JFletcher94]

I'm unable to reproduce this issue. I downloaded https://mods.factorio.com/mod/Velora 1.3.2, and edited planet.lua:

log(serpent.block(velora.map_gen_settings.property_expression_names))
PlanetsLib:extend({ velora })
log(serpent.block(data.raw.planet.velora.map_gen_settings.property_expression_names))

Which logged this output:

   1.127 Script @__Velora__/prototypes/planet.lua:169: {
  enemy_base_frequency = "velora_enemy_base_frequency",
  enemy_base_radius = "velora_enemy_base_radius",
  ["entity:carminite-ore:probability"] = "velora_carminite_ore_probability",
  ["entity:carminite-ore:richness"] = "velora_carminite_ore_richness",
  ["entity:solarite:probability"] = "velora_solarite_probability",
  ["entity:solarite:richness"] = "velora_solarite_richness"
}
   1.128 Script @__Velora__/prototypes/planet.lua:171: {
  enemy_base_frequency = "velora_enemy_base_frequency",
  enemy_base_radius = "velora_enemy_base_radius",
  ["entity:carminite-ore:probability"] = "velora_carminite_ore_probability",
  ["entity:carminite-ore:richness"] = "velora_carminite_ore_richness",
  ["entity:solarite:probability"] = "velora_solarite_probability",
  ["entity:solarite:richness"] = "velora_solarite_richness"
}

Maybe another mod is interfering somehow?