Fix asyncSpawn raiseAssert risk in scheduleDispatch error path

async_postgres/pg_pool.nim

@@ -490,6 +490,20 @@ proc failPendingOp(op: PendingPoolOp, e: ref CatchableError) =
     if not op.queryFut.finished:
       op.queryFut.fail(e)
 
+proc failAllPending(pool: PgPool, e: ref CatchableError) {.raises: [].} =
+  ## Fail every queued op with `e`. Marked `raises: []` so the compiler
+  ## proves the loop cannot leak into an `asyncSpawn`ed caller — any future
+  ## change to `failPendingOp` or the underlying `Future.fail` that could
+  ## raise will be caught here at compile time. `Exception` is used (not
+  ## `CatchableError`) because asyncdispatch's `Future.fail` has inferred
+  ## effect `Exception` via its callback chain.
+  try:
+    while pool.pendingOps.len > 0:
+      let op = pool.pendingOps.popFirst()
+      failPendingOp(op, e)
+  except Exception:
+    discard
+
 proc executeBatch(
     pool: PgPool, conn: PgConnection, batch: seq[PendingPoolOp]
 ): Future[void] {.async.} =
@@ -611,9 +625,7 @@ proc scheduleDispatch(pool: PgPool) {.gcsafe, raises: [].} =
         await pool.dispatchBatchImpl()
       except CatchableError as e:
         # Fail any ops still in the queue so their futures don't hang forever.
-        while pool.pendingOps.len > 0:
-          let op = pool.pendingOps.popFirst()
-          failPendingOp(op, e)
+        pool.failAllPending(e)
       # Re-schedule if there are remaining ops
       if pool.pendingOps.len > 0:
         pool.scheduleDispatch()
@@ -625,12 +637,7 @@ proc scheduleDispatch(pool: PgPool) {.gcsafe, raises: [].} =
         # asyncSpawn should not raise in practice, but the compiler cannot
         # prove it.  Fail any pending ops so their futures do not hang.
         let err = newException(PgError, "Pipeline dispatch failed: " & e.msg)
-        try:
-          while p.pendingOps.len > 0:
-            let op = p.pendingOps.popFirst()
-            failPendingOp(op, err)
-        except Exception:
-          discard
+        p.failAllPending(err)
         p.dispatchScheduled = false
 
   try: