Mjml-cli prints errors to a stdout, and they mix with rendered html code

Mjml-cli currently prints warnings to a stdout, same as the rendered html template. This is a problem because when I compile templates like this mjml index.mjml > index.html, I don’t see any problems, and I risk accidentally sending an email that begins with mjml error messages.

Reproduction Steps:

Create a template with warning, for example by using a mj component in a scope where it doesn’t belong.

Expected behavior:

Errors are sent to stderr (console.error()) while the output appears on stdout (console.log()).

Observed behavior:

Both errors and output is sent to stdout, and errors appear at the beginning of compiled template.

MJML version:

4.1.2

[tkafka]

I disagree with this - stdout should only be used for the actual output (so that you can redirect it to a file, and be sure you aren’t sending your users an email with validation messages).

All diagnostic output should go to stderr, and I propose to add setting to select verbosity (warnings and errors, or errors only).

[kmcb777]

Hi @tkafka it’s true that errors could be sent to stderr, we’ll see for changing that in 4.3 Meanwhile, if you compile with mjml index.mjml -o index.html you have no risk to have errors in the output