Fix: closed Path with blend mode throw error (#1763)

Closes #1755

src/path/Path.js

@@ -2793,16 +2793,19 @@ statics: {
         }
 
         var length = segments.length - (closed ? 0 : 1);
-        for (var i = 1; i < length; i++)
+        if (length > 0) {
+            for (var i = 1; i < length; i++) {
                 addJoin(segments[i], join);
+            }
             if (closed) {
                 // Go back to the beginning
                 addJoin(segments[0], join);
-        } else if (length > 0) {
+            } else {
                 // Handle caps on open paths
                 addCap(segments[0], cap);
                 addCap(segments[segments.length - 1], cap);
             }
+        }
         return bounds;
     },
 

test/tests/Path.js

@@ -653,3 +653,13 @@ test('Path#arcTo(to, radius, rotation, clockwise, large) when from and to are eq
     path.arcTo(point, new Size(10), 0, true, true);
     expect(0);
 });
+
+test('Path#closed with blend mode', function() {
+    new Path({
+        strokeColor: 'black',
+        blendMode: 'negation',
+        closed: true
+    });
+    view.update();
+    expect(0);
+});