Cannot read property 'end' of null

Bug Report

Current Behavior

I’m getting the following error when trying to minify a large file outputted by TypeScript.

TypeError: dist/main.js: Cannot read property 'end' of null
    at _evaluate (node_modules/babel-traverse/lib/path/evaluation.js:160:58)
    at evaluate (node_modules/babel-traverse/lib/path/evaluation.js:65:17)
    at NodePath.evaluate (node_modules/babel-traverse/lib/path/evaluation.js:41:15)
    at evaluateIdentifier (node_modules/babel-helper-evaluate-path/lib/index.js:127:15)
    at evaluate (node_modules/babel-helper-evaluate-path/lib/index.js:19:12)
    at PluginPass.Expression (node_modules/babel-plugin-minify-constant-folding/lib/index.js:165:21)
    at PluginPass.newFn (node_modules/babel-traverse/lib/visitors.js:318:17)
    at newFn (node_modules/babel-traverse/lib/visitors.js:276:21)
    at NodePath._call (node_modules/babel-traverse/lib/path/context.js:76:18)
    at NodePath.call (node_modules/babel-traverse/lib/path/context.js:48:17)

I’ve tracked it down to #4875 which introduces an if statement that compares path.node.start with binding.path.node.end. Note that one side is comparing a property on path, and the other on binding.path.

Changing the right-hand side to path.node.end seems to fix the issue.

Input Code Unfortunately, I discovered this in a closed source repo…

Expected behavior/code I expected the file to be minified and translated to ES2015.

Babel Configuration (.babelrc, package.json, cli command)

{
  "presets": ["es2015", "minify"],
  "comments": false
}

babel dist/main.js --out-file dist/main.min.js

Environment

• Babel version(s): 6.26.0 (babel-core 6.26.0)
• Node/npm version: Node v10.0.0, npm v5.6.0
• OS: macOS 10.13.4
• Monorepo: no
• How you are using Babel: cli

Possible Solution

diff --git a/node_modules/babel-traverse/lib/path/evaluation.js b/node_modules/babel-traverse/lib/path/evaluation.js
index d608418..c05b833 100644
--- a/node_modules/babel-traverse/lib/path/evaluation.js
+++ b/node_modules/babel-traverse/lib/path/evaluation.js
@@ -156,7 +156,7 @@ function evaluate() {
         return deopt(binding.path);
       }
 
-      if (binding && path.node.start < binding.path.node.end) {
+      if (binding && path.node.start < path.node.end) {
         return deopt(binding.path);
       }
 

[kyh]

I was running into the same issue and I managed to fix it by changing my babel-preset-minify version from 0.5.0 -> 0.3.0

[zgr024]

.babelrc

{
  "presets": ["env", "stage-2"],
  "env": {
    "production": {
      "presets": ["minify"]
    }
  }
}

package.json

...
"scripts": {
    "build": "babel src -d build --source-maps inline",
    "build:dist": "NODE_ENV=production babel src -d dist",
    ...
},
"dependencies": {
    "babel-cli": "^6.26.0",
    "babel-core": "^6.26.3",
    "babel-polyfill": "^6.26.0",
    "babel-preset-env": "^1.7.0",
    "babel-preset-minify": "^0.5.0",
    "babel-preset-stage-2": "^6.24.1",
    "babel-register": "^6.26.0",
    ...
}

$ npm run builld:dist