NPE on return statement with no argument

[dounan]

Running the transform on the following code results in a NPE:

function foo() {
  return;
}

TypeError: /Users/dounanshi/dev/babel-plugin-add-react-displayname/test/fixtures/emptyReturn/input.js: Cannot read property 'type' of null
    at doesReturnJSX (/Users/dounanshi/dev/babel-plugin-add-react-displayname/index.js:145:32)
    at PluginPass.FunctionDeclaration (/Users/dounanshi/dev/babel-plugin-add-react-displayname/index.js:13:13)
    at newFn (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/visitors.js:276:21)
    at NodePath._call (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/path/context.js:76:18)
    at NodePath.call (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/path/context.js:48:17)
    at NodePath.visit (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/path/context.js:105:12)
    at TraversalContext.visitQueue (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:150:16)
    at TraversalContext.visitMultiple (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:103:17)
    at TraversalContext.visit (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:190:19)
    at Function.traverse.node (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/index.js:114:17)
    at NodePath.visit (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/path/context.js:115:19)
    at TraversalContext.visitQueue (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:150:16)
    at TraversalContext.visitSingle (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:108:19)
    at TraversalContext.visit (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/context.js:192:19)
    at Function.traverse.node (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/index.js:114:17)
    at traverse (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-traverse/lib/index.js:79:12)
    at File.transform (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-core/lib/transformation/file/index.js:548:35)
    at /Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-core/lib/transformation/pipeline.js:50:19
    at File.wrap (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-core/lib/transformation/file/index.js:564:16)
    at Pipeline.transform (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-core/lib/transformation/pipeline.js:47:17)
    at Object.transformFileSync (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/babel-core/lib/api/node.js:152:10)
    at transformFile (/Users/dounanshi/dev/babel-plugin-add-react-displayname/test/tests.js:31:16)
    at /Users/dounanshi/dev/babel-plugin-add-react-displayname/test/tests.js:15:18
    at Array.forEach (native)
    at Suite.<anonymous> (/Users/dounanshi/dev/babel-plugin-add-react-displayname/test/tests.js:14:31)
    at Object.create (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/lib/interfaces/common.js:114:19)
    at context.describe.context.context (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/lib/interfaces/bdd.js:44:27)
    at Object.<anonymous> (/Users/dounanshi/dev/babel-plugin-add-react-displayname/test/tests.js:12:1)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at /Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/lib/mocha.js:230:27
    at Array.forEach (native)
    at Mocha.loadFiles (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/lib/mocha.js:227:14)
    at Mocha.run (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/lib/mocha.js:513:10)
    at Object.<anonymous> (/Users/dounanshi/dev/babel-plugin-add-react-displayname/node_modules/mocha/bin/_mocha:480:18)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3

A potential fix is to change line 145 to be:

return lastBlock.argument && lastBlock.argument.type === 'JSXElement'

[jasonferrier]

I believe this was addressed in the closed PR: #5