fix: better error if aws-sdk is missing (#43)

Fixes #42

src/aws.ts

@@ -28,7 +28,14 @@ const aws = {
     if (!creds.secretAccessKey) throw new Error('AWS_SECRET_ACCESS_KEY not set')
     return creds
   },
-  get s3() { return cache.s3 = cache.s3 || new (require('aws-sdk/clients/s3') as typeof S3)(this.creds) },
+  get s3() {
+    try {
+      return cache.s3 = cache.s3 || new (require('aws-sdk/clients/s3') as typeof S3)(this.creds)
+    } catch (err) {
+      if (err.code === 'MODULE_NOT_FOUND') throw new Error(`${err.message}\naws-sdk is needed to run this command.\nInstall aws-sdk as a devDependency in your CLI. \`yarn add -D aws-sdk\``)
+      throw err
+    }
+  },
   get cloudfront() { return cache.cloudfront = cache.cloudfront || new (require('aws-sdk/clients/cloudfront') as typeof CloudFront)(this.creds) },
 }
 

src/commands/publish/index.ts

@@ -7,7 +7,10 @@ import {log} from '../../log'
 import * as Tarballs from '../../tarballs'
 
 export default class Publish extends Command {
-  static description = 'publish an oclif CLI to S3'
+  static description = `publish an oclif CLI to S3
+
+"aws-sdk" will need to be installed as a devDependency to publish.
+`
 
   static flags = {
     root: flags.string({char: 'r', description: 'path to oclif CLI root', default: '.', required: true}),