The mod Cities Of Earth 3 (1.7.9) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event CitiesOfEarth3::on_rocket_launched (ID 10)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__CitiesOfEarth3/utils/utils.lua:48: in function 'findSiloByUnitNumber'
CitiesOfEarth3/scripts/coe_silo.lua:111: in function 'getThisRocketSilo'
CitiesOfEarth3/scripts/coe_silo.lua:243: in function <CitiesOfEarth3/scripts/coe_silo.lua:231>

ouch. sorry. I've had that happen and it sucks. I'll look into it this weekend.
Do you have a list of mods? Also, is the save available to share with me?
thanks

Mod list:

name": "base",
enabled": true
name": "Advanced-Electric-Revamped-v16",
enabled": true
name": "Better_Waterfill",
enabled": true
name": "Big_Brother",
enabled": true
name": "bobassembly",
enabled": true
name": "bobclasses",
enabled": true
name": "bobenemies",
enabled": true
name": "bobequipment",
enabled": true
name": "bobinserters",
enabled": true
name": "boblibrary",
enabled": true
name": "BotStart",
enabled": true
name": "Bottleneck",
enabled": true
name": "cargo-ships",
enabled": true
name": "cargo-ships-graphics",
enabled": true
name": "CitiesOfEarth3",
enabled": true
name": "even-distribution",
enabled": true
name": "EvoGUI",
enabled": true
name": "flib",
enabled": true
name": "helmod",
enabled": true
name": "inland_pumps",
enabled": true
name": "Invulnerable-Rails-and-Poles-continued",
enabled": true
name": "LogisticTrainNetwork",
enabled": true
name": "miniloader",
enabled": true
name": "Power Armor MK3",
enabled": true
name": "qol_research",
enabled": true
name": "solar-calc",
enabled": true
name": "sonaxaton-infinite-resources",
enabled": true
name": "SpeedControl",
enabled": true
name": "spidertron-extended",
enabled": true
name": "Squeak Through",
enabled": true
name": "UltimateBelts",
enabled": true
name": "Warehousing",
enabled": true
name": "WhereIsMyBody",
enabled": true

Save file: https://drive.google.com/file/d/1E0Ic6u2aOC0xZlqz1koNYk-j0idhhjmr/view?usp=sharing