Handle boolean params with false default values

[matthewmcgarvey]

Purpose

Fixes #1351

Description

Three places were using the truthiness of param default values when they shouldn't have been. This causes problems when dealing with boolean params. The solution was to always check if the value is a Nop instead.

Checklist

• - An issue already exists detailing the issue/or feature request that this PR fixes
• - All specs are formatted with crystal tool format spec src
• - Inline documentation has been added and/or updated
• - Lucky builds on docker with ./script/setup
• - All builds and specs pass on docker with ./script/test

[jwoertink]

Interesting. I've never seen the Nop before.