Repro with npm run babel
TypeError: src\foo.js: Cannot read property 'bindings' of null at Scope.moveBindingTo (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\scope\index.js:974:12) at BlockScoping.updateScopeInfo (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-plugin-transform-es2015-block-scoping\lib\index.js:364:17) at BlockScoping.run (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-plugin-transform-es2015-block-scoping\lib\index.js:330:12) at PluginPass.BlockStatementSwitchStatementProgram (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-plugin-transform-es2015-block-scoping\lib\index.js:70:24) at newFn (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\visitors.js:236:21) at NodePath._call (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\path\context.js:68:19) at NodePath.call (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\path\context.js:42:17) at NodePath.visit (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\path\context.js:99:12) at TraversalContext.visitQueue (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\context.js:137:18) at TraversalContext.visitSingle (C:\Users\wilkelly\Downloads\babelBug\node_modules\babel-traverse\lib\context.js:96:19)