Cannot read properties of null (reading 'type')

[mureinik]

The defaultTraveler implicitly assumes that a node always has a value.

This is usually true, but no always.

Consider the following:
required dependencies from package.json:

  "dependencies": {
    "@babel/runtime": "^7.23.2",
    "acorn": "^8.11.2",
    "astravel": "^0.6.1"
  }

'use strict';

class MyClass {
    // property with no value - this may look odd, but it's valid syntax
    prop
};

const acorn = require('acorn');
const astravel = require('astravel');

const comments = []
const tree = acorn.parse(MyClass.toString(), {ecmaVersion: 2023, onComment: comments});
astravel.attachComments(tree, comments);

With the current astravel, this will error out:

/home/mureinik/src/git/test-astravel/node_modules/astravel/dist/require/defaultTraveler.js:23
    if (this[node.type]) {
                  ^

TypeError: Cannot read properties of null (reading 'type')
    at Object.go (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/defaultTraveler.js:23:19)
    at Object.MethodDefinition (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/defaultTraveler.js:356:10)
    at attachCommentsToNode (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/attachComments.js:70:25)
    at Object.Block (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/attachComments.js:90:3)
    at Object.go (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/defaultTraveler.js:24:22)
    at Object.ClassDeclaration (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/defaultTraveler.js:305:10)
    at attachCommentsToNode (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/attachComments.js:70:25)
    at Object.Block (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/attachComments.js:90:3)
    at Object.attachComments (/home/allon/src/git/test-astravel/node_modules/astravel/dist/require/attachComments.js:112:22)
    at Object.<anonymous> (/home/allon/src/git/test-astravel/index.js:13:10)