`FieldExtension#after_resolve` returns `nil` for falsy field values (regression in 2.5.24)

[fliebe92]

Describe the bug

FieldExtension#after_resolve uses || to choose between value and values, which treats falsy-but-valid return values (e.g. false) as absent. When a mutation field is declared null: false and resolves to false, the extension returns nil instead, triggering null propagation.

Versions

graphql version: 2.5.24 (regression from 2.5.23)
rails (or other framework): 8.0.5

GraphQL schema

class MyFieldExtension < GraphQL::Schema::FieldExtension
  def resolve(object:, arguments:, context:, **_rest)
    yield(object, arguments)
  end
  # after_resolve NOT overridden — inherits base class default
end

class BaseMutation < GraphQL::Schema::Mutation
  field_class BaseField  # BaseField pushes MyFieldExtension onto every field
end

class Mutations::DoSomething < BaseMutation
  field :success, Boolean, null: false

  def resolve
    { success: false }  # error path
  end
end

GraphQL query

mutation {
  doSomething {
    success
  }
}

Expected response:

{ "data": { "doSomething": { "success": false } } }

Actual response (2.5.24):

{ "data": null, "errors": [{ "message": "Cannot return null for non-nullable field DoSomethingPayload.success" }] }

Steps to reproduce

• Create a mutation with a Boolean, null: false field named success.
• Attach any FieldExtension subclass that does not override after_resolve (inheriting the base class default).
• Execute the mutation through a code path that returns { success: false }.
• Observe the null propagation error. The success: true path is unaffected.

Expected behavior

false is a valid non-null Boolean. A field extension that does not override after_resolve should pass the resolved value through unchanged, as it did in 2.5.23.

Actual behavior

The default after_resolve in 2.5.24 changed from returning value to returning value || values. When value is false, false || nil evaluates to nil, which violates the null: false constraint and nullifies the parent object.

The regression is in this diff between 2.5.23 and 2.5.24:

# 2.5.23

def after_resolve(object:, arguments:, context:, value:, memo:)
  value
end

# 2.5.24

def after_resolve(object: nil, objects: nil, arguments:, context:, values: nil, value: nil, memo:)
  value || values  # ← breaks when value is false
end

[fliebe92]

While composing this one, #5608 got opened. Closing as duplicate.

[rmosolgo]

Hey, thanks so much for reporting this and sorry for the issues. I just released v2.5.25 which includes #5610 to fix this bug. Please let me know if gives you any more trouble!