I created my environment using create-guten-block by Ahmad Awais and compiled it to provide a non minified version of the block.
The following is a fragment of the code with the line of code it was having problems with highlighted.
var _wp$blocks = wp.blocks,
registerBlockType = _wp$blocks.registerBlockType,
InspectorControls = _wp$blocks.InspectorControls; // Import registerBlockType() from wp.blocks
<strong>var BlockControls = wp.editor.BlockControls;</strong>
var Fragment = wp.element.Fragment;
/**