WordPress errors should be on by default

[dgmstuart]

WordPress errors are currently turned off by default and have to be explicitly enabled with

--show-wp-errors=true`​

The reasoning has been that WordPress is too noisy with errors, but I've ended up missing some critical errors while developing Mongoose (which was pretty embarrassing), and I've just had a situation on homeownership where I can see a significant warning (indicating a bug in this case) but Alex couldn't, because he's using the default settings.

Developing using the current default settings seems to be equivalent to developing with define('WP_DEBUG', false); and/or ini_set("display_errors", 0);, which seems to be generally recognised as a Bad Idea.

Might also be worth considering making --no-sql default to false if it's not already, but I'm don't have as clear an argument for that.