Edit: Noticed ERM got updated, will try and see if it fixes it.

I haven't researched Aiur discovery yet.

The mod ERM - Protoss / Akilea (2.0.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event erm_toss::on_trigger_created_entity (ID 26)
erm_toss/control.lua:243: attempt to index local 'source' (a nil value)
stack traceback:
erm_toss/control.lua:243: in function <erm_toss/control.lua:240>

Update:
Still happens with latest version (all mods say up to date), and a small test modlist.
Orbital Ion Cannon (Space Edition), Kux-CoreLib, Space Age, Quality, Elevated Rails, ERM (post process, libraries, asset pack...) ERM Protoss (asset pack), ERM Zerg (asset pack).
Firing an ion cannon causes the same error as above.
Doesn't seem to matter if it hits a biter nest, or empty space.

It will be fix in next release. It should be ready to roll out tomorrow.

newest build should fixed it.