fix(packager): throw errors on an uncompilable entrypoint

Fixes #66

Author: MarshallOfSound

src/api/package.js

@@ -50,6 +50,12 @@ export default async (providedOptions = {}) => {
 
   const packageJSON = await readPackageJSON(dir);
 
+  if (path.dirname(require.resolve(path.resolve(dir, packageJSON.main))) === dir) {
+    console.error(`${packageJSON.main}`.red);
+    // eslint-disable-next-line no-throw-literal
+    throw 'The entrypoint to your application ("packageJSON.name") must be in a subfolder not in the top level directory';
+  }
+
   const forgeConfig = await getForgeConfig(dir);
   let packagerSpinner;