)

A subscriber on the public apm:fastify:middleware:error channel that
re-enters a wrapped hook while handling the error republishes through
publishError, which republishes again, until the stack overflows
(RangeError: Maximum call stack size exceeded during plugin registration).

Two coordinated pieces close it:

1. publishError tracks an in-flight flag and drops the re-entrant publish
   instead of recursing; try/finally clears it even when a subscriber throws.
2. reply.send(error) routes through publishError rather than a bare
   errorChannel.publish, so the response-error path is guarded too.

Drive-by fix:

* preValidation forwards done() when parsingContexts holds no entry, instead
  of dereferencing a missing ctx in processInContext (TypeError when a param
  channel has a subscriber but onRequest took the fast path).

)

A subscriber on the public apm:fastify:middleware:error channel that
re-enters a wrapped hook while handling the error republishes through
publishError, which republishes again, until the stack overflows
(RangeError: Maximum call stack size exceeded during plugin registration).

Two coordinated pieces close it:

1. publishError tracks an in-flight flag and drops the re-entrant publish
   instead of recursing; try/finally clears it even when a subscriber throws.
2. reply.send(error) routes through publishError rather than a bare
   errorChannel.publish, so the response-error path is guarded too.

Drive-by fix:

* preValidation forwards done() when parsingContexts holds no entry, instead
  of dereferencing a missing ctx in processInContext (TypeError when a param
  channel has a subscriber but onRequest took the fast path).

)

A subscriber on the public apm:fastify:middleware:error channel that
re-enters a wrapped hook while handling the error republishes through
publishError, which republishes again, until the stack overflows
(RangeError: Maximum call stack size exceeded during plugin registration).

Two coordinated pieces close it:

1. publishError tracks an in-flight flag and drops the re-entrant publish
   instead of recursing; try/finally clears it even when a subscriber throws.
2. reply.send(error) routes through publishError rather than a bare
   errorChannel.publish, so the response-error path is guarded too.

Drive-by fix:

* preValidation forwards done() when parsingContexts holds no entry, instead
  of dereferencing a missing ctx in processInContext (TypeError when a param
  channel has a subscriber but onRequest took the fast path).

… hook rejections

Fastify boots through avvio, whose `_encapsulateThreeParam` re-invokes an
encapsulated hook after it throws. The same error object rides every re-drive,
and the wrapped hook republishes it on `apm:fastify:middleware:error` each time.
The in-flight boolean added in #8788 only blocks a publish nested inside another
publish; a sequential re-drive runs after the publish returned and its `finally`
cleared the flag, so every re-drive publishes again, the channel subscriber
recurses, and boot dies with `RangeError: Maximum call stack size exceeded`. A
persistent `DatadogRaspAbortError` (appsec RASP) or the boot deprecation warning
is the error that rides the loop.

1. `createErrorPublisher` keeps the boolean for nested re-entry and remembers the
   last published error. The re-drive re-throws the one caught error on every
   hop, so a single reference compare against the previous publish terminates the
   loop where the boolean cannot. This costs one comparison per publish rather
   than a per-publish set lookup, and it does not mutate the error. A distinct
   error still reaches subscribers; only a re-drive alternating two distinct
   persistent errors stays uncollapsed, which is not a shape fastify produces.
2. `invokeHookWithContext`'s async branch returned `publishError(ctx)`, i.e.
   `ctx.error`, from the `.catch` handler, which resolves the promise with the
   error and silently swallows the rejection. It now publishes and re-throws so
   the rejection keeps propagating. The synchronous branch is decoupled the same
   way: publish, then throw the original error rather than throwing the
   publisher's return value.

Fixes: #9099
Refs: #8783