I'm trying to understand how to correctly configure a --proxy-server for chromium and here is what I tried:
google-chrome-stable --disable-gpu --proxy-server="https=a:b@1.2.3.4:55555" --headless --dump-dom https://chromium.org
Running the browser with a totally fake proxy server credentials a:b@1.2.3.4:55555 it keeps dumping the dom which is not expected. By contrast, I expected some error related to the proxy server to occur.