fix(validation): asyncSpawns run

- annotates run with raises: []
- asyncSpawns run, to ensure there are no escaping exceptions

codex/validation.nim

@@ -106,7 +106,7 @@ proc markProofsAsMissing(validation: Validation) {.async.} =
     let previousPeriod = validation.getCurrentPeriod() - 1
     await validation.markProofAsMissing(slotId, previousPeriod)
 
-proc run(validation: Validation) {.async.} =
+proc run(validation: Validation) {.async: (raises: []).} =
   trace "Validation started"
   try:
     while true:
@@ -115,7 +115,7 @@ proc run(validation: Validation) {.async.} =
       await validation.markProofsAsMissing()
   except CancelledError:
     trace "Validation stopped"
-    discard
+    discard # do not propagate as run is asyncSpawned
   except CatchableError as e:
     error "Validation failed", msg = e.msg
 
@@ -124,6 +124,7 @@ proc start*(validation: Validation) {.async.} =
   validation.proofTimeout = await validation.market.proofTimeout()
   await validation.subscribeSlotFilled()
   validation.running = validation.run()
+  asyncSpawn validation.running
 
 proc stop*(validation: Validation) {.async.} =
   await validation.running.cancelAndWait()