TypeError: Cannot read property 'g' of null

I'm using closure-compiler with rollup, for a babel-transpiled library (https://github.com/helion3/inspire-tree). I'm seeing the following errors, both on node v6 and node v7.9.0.

```
java.lang.RuntimeException: java.lang.RuntimeException: INTERNAL COMPILER ERROR. Please report this problem. (TypeError) : Cannot read property 'g' of null Node(FUNCTION map$1): Input_0:5125:0 function map$1(tree, method, args) { Parent(BLOCK): Input_0:12:22 }(this, (function (_) { 'use strict';
Error: Error transforming bundle with 'closure-compiler-js' plugin: java.lang.RuntimeException: java.lang.RuntimeException: INTERNAL COMPILER ERROR. Please report this problem. (TypeError) : Cannot read property 'g' of null Node(FUNCTION map$1): Input_0:5125:0 function map$1(tree, method, args) { Parent(BLOCK): Input_0:12:22 }(this, (function (_) { 'use strict';
at eJ.AG (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:7628:22102)
at eJ.DG (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:7628:22303)
at eJ (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:3482:76)
at FFb (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:4529:86)
at FDb (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:6320:95)
at J6c (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:7255:359)
at tJ (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:1746:29)
at wJ (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:3043:44)
at /Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/jscomp.js:3215:46
at Object.module.exports [as compile] (/Users/viveleroi/Sites/inspire-tree/node_modules/google-closure-compiler-js/compile.js:31:15)
at Object.transformBundle (/Users/viveleroi/Sites/inspire-tree/node_modules/rollup-plugin-closure-compiler-js/dist/rollup-plugin-closure-compiler-js.js:160:50)
at /Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/src/utils/transformBundle.js:10:20
at Array.reduce (native)
at transformBundle (/Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/src/utils/transformBundle.js:4:17)
at Bundle.render (/Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/src/Bundle.js:422:10)
at generate (/Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/src/rollup.js:73:28)
at Object.write (/Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/src/rollup.js:102:20)
at /Users/viveleroi/.nvm/versions/node/v6.1.0/lib/node_modules/rollup/bin/rollup:907:18
```