ruby-grape / grape / 25609200020

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Pull #2703

github

Catch and route exceptions raised inside rescue_from blocks

Resolves #2482. An exception raised inside a `rescue_from` block
used to bubble uncaught and produce the Rack default 500 page. The
middleware now catches it and routes it through one of three paths:

  1. The exception's class has a registered `rescue_from` handler →
     run that handler (with `redispatched: true` so a second raise
     stops the chain — bounded at one redispatch).
  2. The exception is a `Grape::Exceptions::Base` subclass → render
     it via the default Grape error path with its own status and
     message.
  3. Otherwise → fall through to safe_default. The original is
     exposed on `env['grape.exception']` for upstream Rack middleware
     to observe. If the user opted into
     `rescue_from :internal_grape_exceptions do |e| ... end`, that
     handler runs and owns the response. Otherwise the framework
     renders `Grape::Exceptions::InternalServerError` (status 500,
     generic message) — never the original exception's message.

The framework deliberately does no logging of its own for
unhandled internal exceptions. Formatting and destination are
application concerns; the `:internal_grape_exceptions` handler is
where the application opts in to logging, error-tracker forwarding,
or any other observability it cares about.

Adds:
  * `Grape::Exceptions::InternalServerError` — i18n-backed safe
    stand-in.
  * `Grape::Env::GRAPE_EXCEPTION` — env key carrying the original.
  * `rescue_from :internal_grape_exceptions` — DSL opt-in mirroring
    `:grape_exceptions`. Lets the application capture the exception
    and shape the response.

Existing behaviour preserved when the handler returns a non-Response
non-error value (still produces `InvalidResponse` via the default
handler).

UPGRADING note + README rescue_from section document the new
behaviour and the `:internal_grape_exceptions` opt-in.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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