Error getting Hyperclick suggestion: TypeError: Cannot read property 'file' of undefined, coming from babel-core traversal internals

The following exception is caught by the Atom hyperclick package which serves as the base for the Atom js-hyperclick package.

/Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:259 Error getting Hyperclick suggestion: TypeError: Cannot read property 'file' of undefined
    at Scope.checkBlockScopedCollisions (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:412:21)
    at Scope.<anonymous> (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:594:18)
    at Scope.registerBinding (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:608:8)
    at Scope.registerDeclaration (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:537:14)
    at NodePath.Declaration (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:83:36)
    at NodePath.call (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/context.js:56:28)
    at NodePath.visit (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/context.js:90:8)
    at TraversalContext.visitMultiple (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/context.js:108:16)
    at TraversalContext.visit (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/context.js:146:19)
    at Function.traverse.node (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/index.js:76:17)
    at Object.traverse [as default] (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/index.js:55:14)
    at NodePath.traverse (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/index.js:163:23)
    at Scope.crawl (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:821:10)
    at Scope.init (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/scope/index.js:737:32)
    at NodePath.setScope (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/context.js:149:30)
    at NodePath.setContext (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/context.js:168:8)
    at NodePath.unshiftContext (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/path/context.js:273:8)
    at TraversalContext.create (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/context.js:74:10)
    at TraversalContext.visitSingle (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/context.js:131:23)
    at TraversalContext.visit (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/context.js:148:19)
    at Function.traverse.node (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/index.js:76:17)
    at traverse (/Users/sompylasar/.atom/packages/js-hyperclick/node_modules/babel-core/lib/traversal/index.js:55:14)
    at parseCode (/Users/sompylasar/.atom/packages/js-hyperclick/lib/make-cache.js:71:5)
    at Object.get (/Users/sompylasar/.atom/packages/js-hyperclick/lib/make-cache.js:202:34)
    at exports.default (/Users/sompylasar/.atom/packages/js-hyperclick/lib/suggestions.js:193:66)
    at Object.getSuggestionForWord (/Users/sompylasar/.atom/packages/js-hyperclick/lib/js-hyperclick.js:14:24)
    at _ret2.v (/Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:193:24)
    at /Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:22:52
    at undefined.next (native)
    at step (/Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:39:273)
    at /Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:39:443
    at /Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:39:99
    at Hyperclick.getSuggestion (/Users/sompylasar/.atom/packages/hyperclick/lib/Hyperclick.js:169:14)
    at HyperclickForTextEditor.<anonymous> (/Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:246:63)
    at undefined.next (native)
    at step (/Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:17:273)
    at /Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:17:443
    at HyperclickForTextEditor.<anonymous> (/Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:17:99)
    at HyperclickForTextEditor._onKeyDown (/Users/sompylasar/.atom/packages/hyperclick/lib/HyperclickForTextEditor.js:198:14)

The culprit code from the babel-core version js-hyperclick uses which is 5.8.38 assumes that this.hub is present at the time checkBlockScopedCollisions is called, but in some condition (sorry, I could not find the minimal repro) this happens to be false:

  Scope.prototype.checkBlockScopedCollisions = function checkBlockScopedCollisions(local, kind, name, id) {
    // ignore parameters
    if (kind === "param") return;

    // ignore hoisted functions if there's also a local let
    if (kind === "hoisted" && local.kind === "let") return;

    var duplicate = false;

    // don't allow duplicate bindings to exist alongside
    if (!duplicate) duplicate = kind === "let" || local.kind === "let" || local.kind === "const" || local.kind === "module";

    // don't allow a local of param with a kind of let
    if (!duplicate) duplicate = local.kind === "param" && (kind === "let" || kind === "const");

    if (duplicate) {
      throw this.hub.file.errorWithNode(id, messages.get("scopeDuplicateDeclaration", name), TypeError);
    }
  };

The current version of babel-core slightly differs, but still has this assumption.

  checkBlockScopedCollisions(local, kind: string, name: string, id: Object) {
    // ignore parameters
    if (kind === "param") return;

    // ignore hoisted functions if there's also a local let
    if (kind === "hoisted" && local.kind === "let") return;

    let duplicate = false;

    // don't allow duplicate bindings to exist alongside
    if (!duplicate) duplicate = kind === "let" || local.kind === "let" || local.kind === "const" || local.kind === "module";

    // don't allow a local of param with a kind of let
    if (!duplicate) duplicate = local.kind === "param" && (kind === "let" || kind === "const");

    if (duplicate) {
      throw this.hub.file.buildCodeFrameError(id, messages.get("scopeDuplicateDeclaration", name), TypeError);
    }
  }

The this.hub property is assigned once, in the constructor of the Scope, the value is taken from path.hub.

It should come down from the parentPath of the TraversalContext which does not propagate from the root TraversalContext as it should be passed into the traverse function but in js-hyperclick it is not passed.

I’m not sure if this is a bug in js-hyperclick or babel, as the documentation does not mention parentPath, so I am asking a question on the babel repo as well.

[AsaAyers]

Nevermind, no need to open an issue. js-hyperclick normally only responds to things that can be links. Visually you should see your variable underline. When there’s a parse error everything becomes a link and if you try to activate them it will show the error.

[sompylasar]

Cool 👍