Improve Stream error handling #88

README.md

@@ -419,7 +419,9 @@ var counters = sharp.counters(); // { queue: 2, process: 4 }
 
 ### It worked on my machine
 
+```
 npm test
+```
 
 Running the comparative performance tests requires _ImageMagick_ and _GraphicsMagick_.
 

index.js

@@ -331,16 +331,22 @@ Sharp.prototype._sharp = function(callback) {
       // output=stream, input=stream
       this.on('finish', function() {
         sharp.resize(that.options, function(err, data) {
-          if (err) throw err;
+          if (err) {
+            that.emit('error', new Error(err));
+          } else {
             that.push(data);
+          }
           that.push(null);
         });
       });
     } else {
       // output=stream, input=file/buffer
       sharp.resize(this.options, function(err, data) {
-        if (err) throw err;
+        if (err) {
+          that.emit('error', new Error(err));
+        } else {
           that.push(data);
+        }
         that.push(null);
       });
     }

tests/unit.js

@@ -417,6 +417,33 @@ async.series([
     var pipeline = sharp().resize(320, 240);
     readable.pipe(pipeline).pipe(writable);
   },
+  // Stream-Stream error handling
+  function(done) {
+    var pipeline = sharp().resize(320, 240);
+    var anErrorWasEmitted = false;
+    pipeline.on('error', function(err) {
+      anErrorWasEmitted = !!err;
+    }).on('end', function() {
+      assert(anErrorWasEmitted);
+      done();
+    });
+    var readableButNotAnImage = fs.createReadStream(__filename);
+    var writable = fs.createWriteStream(outputJpg);
+    readableButNotAnImage.pipe(pipeline).pipe(writable);
+  },
+  // File-Stream error handling
+  function(done) {
+    var readableButNotAnImage = sharp(__filename).resize(320, 240);
+    var anErrorWasEmitted = false;
+    readableButNotAnImage.on('error', function(err) {
+      anErrorWasEmitted = !!err;
+    }).on('end', function() {
+      assert(anErrorWasEmitted);
+      done();
+    });
+    var writable = fs.createWriteStream(outputJpg);
+    readableButNotAnImage.pipe(writable);
+  },
   // Crop, gravity=north
   function(done) {
     sharp(inputJpg).resize(320, 80).crop(sharp.gravity.north).toFile(path.join(fixturesPath, 'output.gravity-north.jpg'), function(err, info) {