Lighthouse broken when CSP connect-src 'none'

Chrome v64 DEV Tools Audits hangs forever without returning result. Lighthouse v2.8.0 extension would throw error:

VM204:5 Refused to connect to ‘http://example.com/’ because it violates the following Content Security Policy directive: “default-src ‘none’”. Note that ‘connect-src’ was not explicitly set, so ‘default-src’ is used as a fallback.

__nativePromise.resolve.then._ @ VM204:5 Promise.then (async) (anonymous) @ VM204:5 wrapInNativePromise @ VM204:3 (anonymous) @ VM204:21 VM204:5 Refused to connect to ‘http://example.com/’ because it violates the document’s Content Security Policy.

Content-Security-Policy: default-src 'none'; connect-src 'self' would solve the issue, but I think Lighthouse mustn’t break and depend on connect-src ‘self’.

Once was open related issue https://github.com/GoogleChrome/lighthouse/issues/2319

[lukiffer]

It took a while to discover this issue and FWIW, a more descriptive error message would be helpful when the CSP blocks the request as opposed to an HTTP error response.

At a minimum, it would be helpful to add to the documentation for this check under “Common errors include:”

[laukstein]

The same error also in getRobotsTxtContent (Lighthouse v3.0.3) resulting “robots.txt is not valid”

Lighthouse was unable to download your robots.txt file

Refused to connect to 'https://example.com/robots.txt' because it violates the following Content Security Policy directive: "default-src 'none'". Note that 'connect-src' was not explicitly set, so 'default-src' is used as a fallback.

getRobotsTxtContent @ VM1773:7
__nativePromise.resolve.then._ @ VM1773:17
Promise.then (async)
(anonymous) @ VM1773:5
wrapInNativePromise @ VM1773:3
(anonymous) @ VM1773:31