The mod Noxys Multidirectional Trains (0.5.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Noxys_Multidirectional_Trains::on_nth_tick(8)
LuaTrain API call when LuaTrain was invalid.
stack traceback:
[C]: in function 'newindex'
__Noxys_Multidirectional_Trains/control.lua:37: in function 'train_rotate'
Noxys_Multidirectional_Trains/control.lua:46: in function <Noxys_Multidirectional_Trains/control.lua:42>

Can you give me some information on when this happens? This shouldn't happen as far as I'm concerned and I can't reproduce this.

Hopefully this is fixed in 0.5.2. I added some extra protection but I'd still like to know how this happened in the first place.

Can you give me some information on when this happens? This shouldn't happen as far as I'm concerned and I can't reproduce this.

sry, no time to find that out. it crashed almost instantly after loading my game.
*trying 0.5.2 now

well, no crash now, but trains dont leave station. both locs fighting in each direction and the train flickers on trying to leave.

no train limit set there.

Do you have other mods that deal with trains?

just electric trains - which shouldnt affect the existing ones - just adding the "space-variant"

{
"mods":
[

{
  "name": "base",
  "enabled": true
},

{
  "name": "elevated-rails",
  "enabled": true
},

{
  "name": "quality",
  "enabled": true
},

{
  "name": "space-age",
  "enabled": true
},

{
  "name": "aai-loaders",
  "enabled": true
},

{
  "name": "automatic-underground-pipe-connectors",
  "enabled": true
},

{
  "name": "belt-visualizer",
  "enabled": false
},

{
  "name": "better-tank-animation",
  "enabled": true
},

{
  "name": "big-pink-eraser",
  "enabled": true
},

{
  "name": "blueprint-sandboxes",
  "enabled": true
},

{
  "name": "BottleneckLite",
  "enabled": true
},

{
  "name": "brake-squeal-modded",
  "enabled": true
},

{
  "name": "bullet-trails",
  "enabled": true
},

{
  "name": "captains-log",
  "enabled": true
},

{
  "name": "circuit-disconnect",
  "enabled": true
},

{
  "name": "configurable-valves",
  "enabled": true
},

{
  "name": "demolisher-compass",
  "enabled": true
},

{
  "name": "DiscoScience",
  "enabled": true
},

{
  "name": "electric-trains",
  "enabled": true
},

{
  "name": "Enduring-Embers",
  "enabled": true
},

{
  "name": "even-pickier-dollies",
  "enabled": true
},

{
  "name": "EvenDistributionLite",
  "enabled": true
},

{
  "name": "factorio_hd_age_elevated_rails",
  "enabled": true
},

{
  "name": "factorio_hd_age_modpack",
  "enabled": true
},

{
  "name": "factorio_hd_age_quality",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_base",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_decorative",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_enemies_gleba",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_logistics",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_military",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_production",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_terrain_aquilo",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_terrain_fulgora",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_terrain_gleba",
  "enabled": true
},

{
  "name": "factorio_hd_age_space_age_terrain_vulcanus",
  "enabled": true
},

{
  "name": "far-reach",
  "enabled": true
},

{
  "name": "FilterHelper",
  "enabled": true
},

{
  "name": "flib",
  "enabled": true
},

{
  "name": "force-inventory-insert",
  "enabled": true
},

{
  "name": "Infinite_Inserter_Capacity_Bonus_Research",
  "enabled": true
},

{
  "name": "inserter-throughput",
  "enabled": true
},

{
  "name": "inventory-mover",
  "enabled": true
},

{
  "name": "inventory-repair",
  "enabled": true
},

{
  "name": "light-overhaul",
  "enabled": true
},

{
  "name": "lightning-settings",
  "enabled": true
},

{
  "name": "LouderCargoWagons",
  "enabled": true
},

{
  "name": "manual-inventory-sort",
  "enabled": true
},

{
  "name": "MiningScars",
  "enabled": true
},

{
  "name": "nixie-tubes",
  "enabled": true
},

{
  "name": "Noxys_Multidirectional_Trains",
  "enabled": false
},

{
  "name": "play_time_display",
  "enabled": true
},

{
  "name": "pump",
  "enabled": true
},

{
  "name": "Quicksave",
  "enabled": true
},

{
  "name": "railway-reach",
  "enabled": true
},

{
  "name": "RateCalculator",
  "enabled": true
},

{
  "name": "RealisticDecorationCleanup",
  "enabled": true
},

{
  "name": "ReFactorioHD-Base",
  "enabled": true
},

{
  "name": "ReFactorioHD-Logistics",
  "enabled": true
},

{
  "name": "ReFactorioHD-Military",
  "enabled": true
},

{
  "name": "ReFactorioHD-Production",
  "enabled": true
},

{
  "name": "ReFactorioHD-Terrain",
  "enabled": true
},

{
  "name": "shield-projector",
  "enabled": true
},

{
  "name": "signal-display",
  "enabled": true
},

{
  "name": "smooth-artillery-wagon",
  "enabled": true
},

{
  "name": "smooth-cargo-wagon",
  "enabled": true
},

{
  "name": "smooth-fluid-wagon",
  "enabled": true
},

{
  "name": "smooth-trains",
  "enabled": true
},

{
  "name": "smooth_platform_walls",
  "enabled": true
},

{
  "name": "Solar-Lamp",
  "enabled": true
},

{
  "name": "solid-map-ore",
  "enabled": true
},

{
  "name": "squeak-through-2",
  "enabled": true
},

{
  "name": "StatsGui",
  "enabled": true
},

{
  "name": "textplates",
  "enabled": true
},

{
  "name": "tinted-spaceship",
  "enabled": true
},

{
  "name": "tree_collision",
  "enabled": true
},

{
  "name": "VehicleSnap",
  "enabled": true
},

{
  "name": "yemtositemcount",
  "enabled": true
}

]
}

I tried a couple of the mods you listed but am unable to reproduce the issue. Can you post a small world that exhibits the issue?