Error logs are going into stdout

[tugrulates]

Bug Report

I am using zola as part of a larger pipeline. Its stdout cannot be kept quiet while allowing error messages.

Environment

• Zola version: 0.15.3
• Reproduces at the head of both master and next.
• I'm using WSL2.

Expected Behavior

Error logs are sent to stderr, so they can be filtered.

Current Behavior

Both normal and error logs are sent to stdout.

Step to reproduce

Force an error with an empty config.

$ echo > config.toml
$ zola build 1> /dev/null
$ zola build 2> /dev/null
Building site...
Failed to build the site
Error: A base URL is required in config.toml with key `base_url`

I can also reproduce with a Tera syntax error.