Rollup: Don't include source code in distribution.

package.json

@@ -5,7 +5,7 @@
   "main": "main.js",
   "scripts": {
     "dev": "rollup --config rollup.config.js -w",
-    "build": "rollup --config rollup.config.js"
+    "build": "rollup --config rollup.config.js --environment BUILD:production"
   },
   "keywords": [],
   "author": "",

rollup.config.js

@@ -2,6 +2,8 @@ import typescript from '@rollup/plugin-typescript';
 import {nodeResolve} from '@rollup/plugin-node-resolve';
 import commonjs from '@rollup/plugin-commonjs';
 
+const isProd = (process.env.BUILD === 'production');
+
 const banner = 
 `/*
 THIS IS A GENERATED/BUNDLED FILE BY ROLLUP
@@ -14,6 +16,7 @@ export default {
   output: {
     dir: '.',
     sourcemap: 'inline',
+    sourcemapExcludeSources: isProd,
     format: 'cjs',
     exports: 'default',
     banner,