TypeError Cannot read property 'type' of null at ReturnStatement no-async-in-computed-properties

[axit-joost]

Tell us about your environment

• ESLint version: 5.13.0
• eslint-plugin-vue version: 5.2.0
• Node version: 10.2

Please show your full configuration:

{
    "extends": [
        "airbnb-base",
        "plugin:vue/recommended",
        "plugin:prettier/recommended",
        "prettier/vue"
    ],
    "env": {
        "browser": true,
        "node": true,
        "jasmine": true
    },
    "rules": {
        "prettierOptions": {
            "printWidth": 120
        },
        "no-underscore-dangle": 0
    }
}

What did you do?

It happened in two separate occasions during work. I am using vscode by the way, with the eslint extension.

1. While specifying a Prop Type and its default value while typing, the TypeError occurs when defining default() { return ... }

2. It also happened while refactoring old legacy code that had a return without a return value.

methods: {
  foo() {
    if (this.data.prop === 'someValue') return;
  }
}

What did you expect to happen?
No TypeError and continue linting process.

What actually happened?
TypeError and linting processing stopped with a stack trace.

Here's the stacktrace from the ESLint output of the vscode extension:

[Error - 4:12:58 PM] TypeError: Cannot read property 'type' of null
    at ReturnStatement (/Users/joost/Code/some-project/node_modules/eslint-plugin-vue/lib/rules/no-async-in-computed-properties.js:141:31)
    at listeners.(anonymous function).forEach.listener (/Users/joost/Code/some-project/node_modules/eslint/lib/util/safe-emitter.js:45:58)
    at Array.forEach (<anonymous>)
    at Object.emit (/Users/joost/Code/some-project/node_modules/eslint/lib/util/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/Users/joost/Code/some-project/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/Users/joost/Code/some-project/node_modules/eslint/lib/util/node-event-generator.js:280:22)
    at NodeEventGenerator.enterNode (/Users/joost/Code/some-project/node_modules/eslint/lib/util/node-event-generator.js:294:14)
    at CodePathAnalyzer.enterNode (/Users/joost/Code/some-project/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:632:23)
    at nodeQueue.forEach.traversalInfo (/Users/joost/Code/some-project/node_modules/eslint/lib/linter.js:750:28)
    at Array.forEach (<anonymous>)

The offending code in the rules' source:

        'ReturnStatement' (node) {
          if (
                node.argument.type === 'ObjectExpression' ||
                node.argument.type === 'ArrayExpression'
          ) {
            allowedScopes.push(node.argument)
          }
        }

So if I am reading this correctly, argument appears to be null, hence the error?

It is always that portion of no-async-in-computed-properties rule, which would suggest it being some sort of issue with the computed properties. I had to comment out portions of that ugly legacy Vue component to target the offending code, which was the return; without a value.

But throughout the day, I got the same stacktrace occurring while adding PropTypes and their default values (as is recommended by 'plugin:vue/recommended')

Any ideas or suggestions?

[axit-joost]

Closed as it is fixed in #816