When I try to print `msg.text` in 'console' event with type 'error', I got `JSHandle@error`

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 1.9.0
• Platform / OS version: macos
• URLs (if applicable):
• Node.js version: 8.11.3

What steps will reproduce the problem?

Please include code that reproduces the issue.

1. Simply add these code in your page

try {
    // try to print a value doesn't exist
    // and it will throw an error
    console.log(a)
} catch (e) {
    // catch the error and print this with `console.error`
    console.error(e)
}

1. puppeteer script:

...
page.on('console', msg => {
    console.log(msg.text())
})
...

What is the expected result? It prints JSHandle@error

What happens instead? The exact error object like ReferenceError: a is not defined...

[tompere]

@SidKwok you can use msg.args() to retrieve the array of arguments passed to console.

BUT, since errors are not serializeable it won’t return the desired value. you can however, use the following as a workaround:

page.on('console', async msg => {
  const args = await msg.args()
  args.forEach(async (arg) => {
    const val = await arg.jsonValue()
    // value is serializable
    if (JSON.stringify(val) !== JSON.stringify({})) console.log(val)
    // value is unserializable (or an empty oject)
    else {
      const { type, subtype, description } = arg._remoteObject
      console.log(`type: ${type}, subtype: ${subtype}, description:\n ${description}`)
    }
  })
});

[aslushnikov]

Yeah I agree, we should probably do a better job on getting error texts and everything. The way it’s supposed to be done atm is like this:

page.on('console', async msg => {
  // serialize my args the way I want
  const args = await Promise.all(msg.args.map(arg => arg.executionContext().evaluate(arg => {
    // I'm in a page context now. If my arg is an error - get me its message.
    if (arg instanceof Error)
      return arg.message;
    // return arg right away. since we use `executionContext.evaluate`, it'll return JSON value of
    // the argument if possible, or `undefined` if it fails to stringify it.
    return arg;
  }, arg)));
  console.log(...args);
});