Prevent using integers or numeric strings as keys

[tangrufus]

• [x] I've read the guidelines for Contributing to Roots Projects
• [x] This request isn't a duplicate of an existing issue
• [x] I've read the docs and followed them (if applicable)
• [x] This is not a personal support request that should be posted on the Roots Discourse community

Description

Unexpected behaviors when using integers or numeric strings as keys

Steps to reproduce

// Without declare(strict_types=1); !!
Config::define(999, 'nine nine nine');
Config::apply();

Expected behavior:

Warn (or throw exceptions) about using integers or numeric strings as keys is incorrect.

Actual behavior:

echo Config::get(999);
==> nine nine nine

echo constant(999);
==> nine nine nine

echo constant('999');
==> nine nine nine

echo 999;
==> 999

Possible Solution

• Bump PHP requirement
• Add declare(strict_types=1);
• Add type hints

[austinpray]

@TangRufus I'm down for doing all this

• Bump PHP requirement
• Add declare(strict_types=1);
• Add type hints

Let's do it and tag a 2.0?