Send parse error to Promise reject too

lib/lazy-result.js

@@ -24,7 +24,11 @@ export default class LazyResult {
                 opts.map = { prev: css.map };
             }
         } else {
-            root = parse(css, opts);
+            try {
+                root = parse(css, opts);
+            } catch (error) {
+                this.parseError = error;
+            }
         }
 
         this.result = new Result(processor, root, opts);
@@ -87,7 +91,13 @@ export default class LazyResult {
 
     async() {
         if ( this.processed ) {
-            return Promise.resolve().then( () => this.stringify() );
+            return new Promise( (resolve, reject) => {
+                if ( this.parseError ) {
+                    reject(this.parseError);
+                } else {
+                    resolve(this.stringify());
+                }
+            });
         }
         if ( this.processing ) {
             return this.processing;
@@ -95,6 +105,7 @@ export default class LazyResult {
 
         let plugins = this.processor.plugins.slice(0);
         this.processing = new Promise( (resolve, reject) => {
+            if ( this.parseError ) return reject(this.parseError);
             this.asyncTick(plugins, resolve, reject);
         }).then( () => {
             this.processed = true;
@@ -112,6 +123,8 @@ export default class LazyResult {
             throw 'Use process(css).then(cb) to work with async plugins';
         }
 
+        if ( this.parseError ) throw this.parseError;
+
         for ( let plugin of this.result.processor.plugins ) {
             let promise = this.run(plugin);
             if ( isPromise(promise) ) {

test/processor.js

@@ -105,7 +105,7 @@ describe('Processor', () => {
         it('throws with file name', () => {
             let error;
             try {
-                (new Processor()).process('a {', { from: 'a.css' });
+                (new Processor()).process('a {', { from: 'a.css' }).css;
             } catch (e) {
                 if ( e instanceof CssSyntaxError ) {
                     error = e;
@@ -267,6 +267,13 @@ describe('Processor', () => {
             });
         });
 
+        it('throws parse error in async', (done) => {
+            (new Processor()).process('a{').catch(function (err) {
+                expect(err.message).to.eql('<css input>:1:1: Unclosed block');
+                done();
+            });
+        });
+
         it('throws error on sync method to async plugin', () => {
             let async = () => {
                 return new Promise( (resolve) => resolve() );