Using Factorissimo2 version 2.1.1 / Factorio 1.15.3
The error only happens with wave-defense, all other scenarios load fine, and disabling Factorissimo2 solves the issue.

Error while running the on_init: Error while running event Factorissimo2::on_research_finished (ID 18)
Factorissimo2/control.lua:1019: bad argument #1 to 'pairs' (table expected, got nil)
stack traceback:
...loads/Factorio_0.15.3/temp/currently-playing/control.lua:740: in function 'set_research'
...loads/Factorio_0.15.3/temp/currently-playing/control.lua:122: in function 'init_forces'
...loads/Factorio_0.15.3/temp/currently-playing/control.lua:22: in function <...loads/Factorio_0.15.3/temp/currently-playing/control.lua:19>

Ah, I see, the wave-defense's on_init() does a research_all_technologies(), which causes my startup methods to be called in the wrong order. Thanks for the report.