local myTestImport = require "MyDirectory/MyFile" -- Throws exception

[Kronn8]

THE PROBLEM

I'm trying to refactor my old AddOn into multiple files.

When I run `> lua MyAddon.lua` from the command line, it runs as expected, spitting out "Hello World".

However, I get the familiar "function expected instead of nil" error when the UI loads.

My directory structure:

Elder Scrolls Online\live\AddOns
  |
  +-- MyAddon\
        |
        +-- MyAddon.lua
        |
        +-- MyDirectory\
              |
              +--MyFile.lua

`MyAddon.lua` contains

local myTestImport = require "MyDirectory/MyFile" -- Exception: function expected instead of nil
print(myTestImport)

And `MyFile.lua` contains

return "Hello World"

THE SOLUTION

There was more wrong with my code than I thought. Here's what worked:

`MyAddon.txt` contains

## Title: MyAddon
## Author: Kronn8
## APIVersion: 100026

MyDirectory\MyFile.lua
FreeMyInventory.lua

`MyAddon.lua` contains

MyAddon = MyAddon or {}
MyAddon.name = "MyAddon"
 
-- Load files (optional, but otherwise, you'll have to use MyAddon.MyFile each time you want to use MyFile)
local MyFile = MyAddon.MyFile
 
function MyAddon:confirmStartup()
    d(MyFile)
end
 
EVENT_MANAGER:RegisterForEvent(MyAddon.name, EVENT_PLAYER_ACTIVATED, MyAddon.confirmStartup)

And `MyFile.lua` contains

MyAddon = MyAddon or {}
 
local message = "Hello World"
 
MyAddon.MyFile = message