Allow plugin directories to be optional

Using gluegun@2.0.0-alpha.2, I have this in my runtime config:

    .plugin(resolve(`${filesystem.cwd()}`, BRAND), LOAD_OPTIONS)

But I want that to be optional as it may not exist.

Here’s the error it spits out:

Error: Error: couldn't load plugin (not a directory): /Users/steve/src/ir/app-machine/app-machine
    at loadFromDirectory (/Users/steve/src/ir/app-machine/node_modules/gluegun/src/loaders/toml-plugin-loader.js:40:11)
    at Runtime.load (/Users/steve/src/ir/app-machine/node_modules/gluegun/src/domain/runtime.js:184:20)
    at loadPlugins.forEach.entry (/Users/steve/src/ir/app-machine/node_modules/gluegun/src/domain/builder.js:56:19)
    at Array.forEach (<anonymous>)
    at Builder.create (/Users/steve/src/ir/app-machine/node_modules/gluegun/src/domain/builder.js:50:22)
    at Object.configureRuntime (/Users/steve/src/ir/app-machine/src/cli/gluegun-runtime.ts:20:6)
    at Object.<anonymous> (/Users/steve/src/ir/app-machine/src/cli/cli.ts:24:21)
    at step (/Users/steve/src/ir/app-machine/src/cli/cli.ts:32:23)
    at Object.next (/Users/steve/src/ir/app-machine/src/cli/cli.ts:13:53)
    at /Users/steve/src/ir/app-machine/src/cli/cli.ts:7:71

For src I can see why it’s required, but for plugin and plugins, it should be optional.

[skellock]

Sure! I was thinking of options having an extra property called required which wouldn’t be there (so falsy) by default. But in loadDefault, it would be required: true.

I think. Haha.

[WilliamStephens]

Hey, I would love to take this one!