diff --git a/.gitignore b/.gitignore
index 6875798..00989a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,8 +1,12 @@
 
 *.DS_Store
 
-jspm_packages/*
+jspm_packages
 
-node_modules/*
+node_modules
+
+lib
+
+module
 
 bundle.js
diff --git a/src/Slicer.js b/src/Slicer.js
index 4da1f01..d100150 100644
--- a/src/Slicer.js
+++ b/src/Slicer.js
@@ -4,7 +4,7 @@ import SlicerWorker from './slicerWorker.js!worker';
 
 export function sliceMesh(settings, mesh, sync = false, onProgress) {
   if (typeof mesh === 'undefined' || !mesh.isMesh) {
-    throw new Error('Provide mesh is not intance of THREE.Mesh');
+    throw new Error('Provided mesh is not intance of THREE.Mesh');
   }
 
   mesh.updateMatrix();
@@ -23,6 +23,10 @@ export function sliceGeometry(settings, geometry, matrix, sync = false, onProgre
     throw new Error('Geometry is not an instance of BufferGeometry or Geometry');
   }
 
+  if (geometry.faces.length === 0) {
+    throw new Error('Geometry does not contain any data');
+  }
+
   if (matrix) {
     geometry.applyMatrix(matrix);
   }
@@ -42,7 +46,11 @@ function sliceAsync(settings, geometry, onProgress) {
   return new Promise((resolve, reject) => {
     // create the slicer worker
     const slicerWorker = new SlicerWorker();
-    slicerWorker.onerror = reject;
+
+    slicerWorker.onerror = error => {
+      slicerWorker.terminate();
+      reject(error);
+    };
 
     // listen to messages send from worker
     slicerWorker.addEventListener('message', (event) => {
@@ -63,11 +71,12 @@ function sliceAsync(settings, geometry, onProgress) {
     });
 
     // send geometry and settings to worker to start the slicing progress
+    geometry = geometry.toJSON();
     slicerWorker.postMessage({
       message: 'SLICE',
       data: {
         settings,
-        geometry: geometry.toJSON()
+        geometry
       }
     });
   });
diff --git a/src/sliceActions/addBrim.js b/src/sliceActions/addBrim.js
index 9812598..da66540 100644
--- a/src/sliceActions/addBrim.js
+++ b/src/sliceActions/addBrim.js
@@ -15,11 +15,10 @@ export default function addBrim(slices, settings) {
 
   const [firstLayer] = slices;
 
-  firstLayer.brim = firstLayer.parts.reduce((brim, { shape }) => {
+  firstLayer.brim = firstLayer.parts.reduce((brim, { shape }) => (
     brim.join(shape.offset(brimOffset, {
       ...offsetOptions,
       endType: shape.closed ? 'etClosedPolygon' : 'etOpenRound'
-    }));
-    return brim;
-  }, new Shape([], true)).simplify('pftNonZero');
+    }))
+  ), new Shape([], true)).simplify('pftNonZero');
 }
diff --git a/src/sliceActions/optimizePaths.js b/src/sliceActions/optimizePaths.js
index cc5fec5..5a478b4 100644
--- a/src/sliceActions/optimizePaths.js
+++ b/src/sliceActions/optimizePaths.js
@@ -21,12 +21,8 @@ export default function optimizePaths(slices, settings) {
       for (let i = 0; i < slice.parts.length; i ++) {
         const part = slice.parts[i];
 
-        let bounds;
-        if (part.shape.closed) {
-          bounds = part.outerLine.shapeBounds();
-        } else {
-          bounds = part.shape.shapeBounds();
-        }
+        const shape = part.shape.closed ? part.outerLine : part.shape;
+        const bounds = shape.shapeBounds();
 
         const top = bounds.top - start.y;
         const bottom = start.y - bounds.bottom;
@@ -41,7 +37,7 @@ export default function optimizePaths(slices, settings) {
         }
       }
 
-      const part = slice.parts.splice(closestPart, 1)[0];
+      const [part] = slice.parts.splice(closestPart, 1);
       parts.push(part);
 
       if (part.shape.closed) {