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Cannot read property 'add' of undefined

See original GitHub issue

seeing " Cannot read property ‘add’ of undefined" with the latest

sample code, junk.js

const y = () => {};
function x(foo = y) {}

command: npx babel junk.js --presets=minify

package.json

{
  "name": "babelbug",
  "version": "1.0.0",
  "description": "",
  "devDependencies": {
    "@babel/core": "^7.7.0",
    "@babel/preset-env": "^7.7.0",
    "@babel/cli": "^7.7.0",
    "babel-preset-minify": "~0.5.0"
  }
}

stack

{ TypeError: C:\babelbug\junk.js: Cannot read property 'add' of undefined
    at ScopeTracker.addReference (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\scope-tracker.js:47:34)
    at ReferencedIdentifier (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\index.js:196:26)
    at newFn (C:\babelbug\node_modules\@babel\traverse\lib\visitors.js:220:17)
    at bfsTraverse (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\bfs-traverse.js:32:43)
    at Mangler.collect (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\index.js:229:7)
    at Mangler.run (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\index.js:54:12)
    at PluginPass.exit (C:\babelbug\node_modules\babel-plugin-minify-mangle-names\lib\index.js:558:19)
    at newFn (C:\babelbug\node_modules\@babel\traverse\lib\visitors.js:179:21)
    at NodePath._call (C:\babelbug\node_modules\@babel\traverse\lib\path\context.js:55:20)
    at NodePath.call (C:\babelbug\node_modules\@babel\traverse\lib\path\context.js:42:17) code: 'BABEL_TRANSFORM_ERROR' }

Issue Analytics

State:
Created 4 years ago
Reactions:18
Comments:20

Top GitHub Comments

4reactions

mjakobiscommented, Jan 21, 2020

The issue seems to be with default functional parameters set to a constant.

2reactions

somewhatabstractcommented, Feb 17, 2020

I see the same issue when using rollup-babel-minify. Dependabot tried to update to latest babel and couldn’t due to this issue.

TypeError: unknown: Cannot read property 'add' of undefined
    at ScopeTracker.addReference (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/scope-tracker.js:47:34)
    at ReferencedIdentifier (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/index.js:196:26)
    at newFn (/Users/jeffyates/git/checksync/node_modules/@babel/traverse/lib/visitors.js:220:17)
    at bfsTraverse (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/bfs-traverse.js:32:43)
    at Mangler.collect (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/index.js:229:7)
    at Mangler.run (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/index.js:54:12)
    at PluginPass.exit (/Users/jeffyates/git/checksync/node_modules/babel-plugin-minify-mangle-names/lib/index.js:558:19)
    at newFn (/Users/jeffyates/git/checksync/node_modules/@babel/traverse/lib/visitors.js:179:21)
    at NodePath._call (/Users/jeffyates/git/checksync/node_modules/@babel/traverse/lib/path/context.js:55:20)
    at NodePath.call (/Users/jeffyates/git/checksync/node_modules/@babel/traverse/lib/path/context.js:42:17)