fix: last nits

ffi/event_thread.nim

@@ -47,7 +47,8 @@ proc emitLivenessEvent[T, P](ctx: ptr FFIContext[T], name: string, payload: P) =
       chronicles.error "liveness event encode failed", name = name, err = exc.msg
       return
   let dataPtr: pointer =
-    if event.len > 0: unsafeAddr event[0] else: nil
+    if event.len > 0: cast[pointer](unsafeAddr event[0])
+    else: cast[pointer](emptyListenerPayload)
   ctx.dispatchToListeners(name, dataPtr, event.len)
 
 proc onNotResponding*(ctx: ptr FFIContext) =

ffi/ffi_context.nim

@@ -106,7 +106,7 @@ proc deinitContextResources*[T](ctx: ptr FFIContext[T]): Result[void, string] =
     if not ctx.eventThreadExitSignal.isNil():
       ?ctx.eventThreadExitSignal.close()
       ctx.eventThreadExitSignal = nil
-  ok()
+  return ok()
 
 proc cleanUpResources[T](ctx: ptr FFIContext[T]): Result[void, string] =
   ## Full cleanup for heap-allocated contexts: closes all resources and frees memory.
@@ -178,7 +178,7 @@ proc initContextResources*[T](ctx: ptr FFIContext[T]): Result[void, string] =
     return err("failed to create the event thread: " & getCurrentExceptionMsg())
 
   success = true
-  ok()
+  return ok()
 
 proc signalStop*[T](ctx: ptr FFIContext[T]): Result[void, string] =
   # Error paths intentionally skip onNotResponding: a back-pressuring
@@ -199,7 +199,7 @@ proc signalStop*[T](ctx: ptr FFIContext[T]): Result[void, string] =
     error "failed to signal eventQueueSignal in signalStop", error = evtSignaled.error
   elif evtSignaled.get() == false:
     error "failed to signal eventQueueSignal on time in signalStop"
-  ok()
+  return ok()
 
 ## If the FFI thread's event loop is blocked by a synchronous handler
 ## (e.g. blocking I/O), it cannot process reqSignal in time to exit.
@@ -233,7 +233,7 @@ proc stopAndJoinThreads*[T](ctx: ptr FFIContext[T]): Result[void, string] =
     return err("event thread did not exit in time; leaking ctx to avoid hang")
 
   joinThread(ctx.eventThread)
-  ok()
+  return ok()
 
 proc clearContext[T](ctx: ptr FFIContext[T]): Result[void, string] =
   ## Stops the FFI context that was created via createFFIContext[T]() (heap).
@@ -241,4 +241,4 @@ proc clearContext[T](ctx: ptr FFIContext[T]): Result[void, string] =
     return err("clearContext: " & $error)
   ctx.cleanUpResources().isOkOr:
     return err("cleanUpResources failed: " & $error)
-  ok()
+  return ok()

ffi/ffi_events.nim

@@ -203,7 +203,7 @@ proc eventQueueLen*(q: var EventQueue): int {.raises: [], gcsafe.} =
     return q.count
 
 
-const emptyListenerPayload: cstring = ""
+const emptyListenerPayload*: cstring = ""
   ## Non-nil zero-length buffer handed to listeners when a payload is
   ## empty, so a consumer doing `std::string(data, len)` / `memcpy` never
   ## receives a nil pointer (which is UB even at len 0).
@@ -225,7 +225,8 @@ proc notifyListenersErr*(listeners: seq[FFIEventListener], msg: string) =
   ## Error fan-out: adapts the message string to `notifyListeners`, which
   ## supplies the non-nil pointer for the empty-message case.
   let p =
-    if msg.len > 0: cast[pointer](unsafeAddr msg[0]) else: nil
+    if msg.len > 0: cast[pointer](unsafeAddr msg[0])
+    else: cast[pointer](emptyListenerPayload)
   notifyListeners(listeners, RET_ERR, p, msg.len)
 
 var ffiCurrentEventRegistry* {.threadvar.}: ptr FFIEventRegistry
@@ -266,7 +267,8 @@ template dispatchFFIEvent*(eventName: string, body: untyped) =
   withFFIEventDispatch(eventName, listeners):
     let event = body
     let dataPtr: pointer =
-      if event.len > 0: unsafeAddr event[0] else: nil
+      if event.len > 0: cast[pointer](unsafeAddr event[0])
+      else: cast[pointer](emptyListenerPayload)
     notifyListeners(listeners, RET_OK, dataPtr, event.len)
 
 template dispatchFFIEventCbor*(eventName: string, eventPayload: typed) =