fix: return early as expected when engine.Prepare fails (scroll-tech#886

)

miner/scroll_worker.go

@@ -373,12 +373,12 @@ func (w *worker) startNewPipeline(timestamp int64) {
 		header.Coinbase = w.coinbase
 	}
 
-	common.WithTimer(prepareTimer, func() {
-		if err := w.engine.Prepare(w.chain, header); err != nil {
-			log.Error("Failed to prepare header for mining", "err", err)
-			return
-		}
-	})
+	prepareStart := time.Now()
+	if err := w.engine.Prepare(w.chain, header); err != nil {
+		log.Error("Failed to prepare header for mining", "err", err)
+		return
+	}
+	prepareTimer.UpdateSince(prepareStart)
 
 	// If we are care about TheDAO hard-fork check whether to override the extra-data or not
 	if daoBlock := w.chainConfig.DAOForkBlock; daoBlock != nil {