Unexpected error when default value throws an error

[matthewmcgarvey]

Say you have a default setting that can fail occasionally (in this example it fails every time but you get the point):

class MyClass
  Habitat.create do
    setting my_setting : String = raise "OOPS!"
  end
end

When you call MyClass.new, you'd expect the error to raise that comes from the default argument. Instead, you get:

Recursion while initializing class variables and/or constants (Exception)
         from /usr/local/Cellar/crystal/0.34.0/src/crystal/once.cr:21:9 in 'once'
         from /usr/local/Cellar/crystal/0.34.0/src/crystal/once.cr:48:3 in '__crystal_once'
         from ~MyClass::Settings::my_setting:read
         from spec/habitat_spec.cr:51:3 in 'broken_setting?'
         from src/habitat.cr:29:3 in 'raise_if_missing_settings!'
         from spec/habitat_spec.cr:151:5 in '->'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/example.cr:255:3 in 'internal_run'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/example.cr:35:16 in 'run'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/context.cr:296:23 in 'internal_run'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/context.cr:291:7 in 'run'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/context.cr:48:23 in 'run'
         from /usr/local/Cellar/crystal/0.34.0/src/spec/dsl.cr:270:7 in '->'
         from /usr/local/Cellar/crystal/0.34.0/src/crystal/at_exit_handlers.cr:255:3 in 'run'
         from /usr/local/Cellar/crystal/0.34.0/src/crystal/main.cr:45:14 in 'main'
         from /usr/local/Cellar/crystal/0.34.0/src/crystal/main.cr:114:3 in 'main'

[jwoertink]

Alright, so looking in to this, I noticed a different issue in Crystal reported here.

To solve this for now, we can catch if it raises, but then what happens is instead of getting your "OOPS!", you'll get

The 'my_setting' setting for MyClass was nil, but the setting is required

That's probably ok for the time being, and at least a lot more helpful. What do you think @matthewmcgarvey ?

[matthewmcgarvey]

I like that 👍