Loam cannot be run under Node.js

Hi

I want to use this in node.JS environment on local Windows PC, not on web browser.

Just for test, I wrote such ad-hoc code (without webpack or any packaging) and run:
```
const loam = require("loam")
loam.initialize()

const main = async () => {

const file = 'png/Nara-Genpyo.png'
const dataset = await loam.open(file)
const width = await dataset.width()
console.log(width)
}

main()
```

The result is error follow:
```
ReferenceError: self is not defined
at Object. (F:\github\loam\node_modules\loam\lib\loam.js:1:197)
at Module._compile (node:internal/modules/cjs/loader:1101:14)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
at Module.load (node:internal/modules/cjs/loader:981:32)
at Function.Module._load (node:internal/modules/cjs/loader:822:12)
at Module.require (node:internal/modules/cjs/loader:1005:19)
at require (node:internal/modules/cjs/helpers:102:18)
at Object. (F:\github\loam\index.js:1:14)
at Module._compile (node:internal/modules/cjs/loader:1101:14)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
```

I changed the code like this, but still same error occurs.
```
const main = async () => {
const loam = await import("loam")
loam.initialize()

const file = 'png/Nara-Genpyo.png'
const dataset = await loam.open(file)
const width = await dataset.width()
console.log(width)
}

main()
```

Is this expected result?
Loam don't work in node.js environment or it always must be used with webpack-like packager?

Start by reproducing the Windows Node.js example using the package entry point in index.js, then inspect the failing bundle at node_modules/loam/lib/loam.js where the self ReferenceError occurs. Verify whether both require("loam") and import("loam") reach initialize and dataset.width without the browser-only error; no test file is mentioned in the issue.

Written by the indexing model from the issue text.