Add error message when reexporting missing identifier

src/Module.js

@@ -194,6 +194,7 @@ export default class Module {
 			else {
 				node.specifiers.forEach( specifier => {
 					this.reexports[ specifier.exported.name ] = {
+						start: specifier.start,
 						source,
 						localName: specifier.local.name,
 						module: null // filled in later
@@ -724,7 +725,16 @@ export default class Module {
 		// export { foo } from './other.js'
 		const reexportDeclaration = this.reexports[ name ];
 		if ( reexportDeclaration ) {
-			return reexportDeclaration.module.traceExport( reexportDeclaration.localName );
+			const declaration = reexportDeclaration.module.traceExport( reexportDeclaration.localName );
+
+			if ( !declaration ) {
+				const err = new Error( `'${reexportDeclaration.localName}' is not exported by '${reexportDeclaration.module.id}' (imported by '${this.id}')` );
+				err.file = this.id;
+				err.loc = getLocation( this.code, reexportDeclaration.start );
+				throw err;
+			}
+
+			return declaration;
 		}
 
 		const exportDeclaration = this.exports[ name ];

test/function/reexport-missing-error/_config.js

@@ -0,0 +1,8 @@
+var assert = require( 'assert' );
+
+module.exports = {
+	description: 'reexporting a missing identifier should print an error',
+	error: function ( error ) {
+		assert.ok( /^'foo' is not exported/.test( error.message ) );
+	}
+};

test/function/reexport-missing-error/empty.js

@@ -0,0 +1 @@
+// this space left intentionally blank

test/function/reexport-missing-error/main.js

@@ -0,0 +1 @@
+export { foo as bar } from './empty.js';