Fix CMD+A backspace issue

- Closes #272

lib/constants.js

@@ -461,5 +461,6 @@ export const DEFAULT_SETTINGS = {
   lineNumbers: false,
   exportSize: '2x',
   titleBar: '',
-  watermark: false
+  watermark: false,
+  squaredImage: false
 }

pages/editor.js

@@ -238,7 +238,7 @@ class Editor extends React.Component {
                   onAspectRatioChange={this.updateAspectRatio}
                   updateTitleBar={this.updateTitleBar}
                 >
-                  {this.state.code || DEFAULT_CODE}
+                  {this.state.code != null ? this.state.code : DEFAULT_CODE}
                 </Carbon>
               </Overlay>
             )}