fix call flat receipt

Signed-off-by: jsvisa <delweng@gmail.com>

eth/tracers/native/call_flat.go

@@ -211,14 +211,17 @@ func (t *flatCallTracer) OnTxStart(env *tracing.VMContext, tx *types.Transaction
 }
 
 func (t *flatCallTracer) OnTxEnd(receipt *types.Receipt, err error) {
+	if t.interrupt.Load() {
+		return
+	}
+	// Set the context for the tracer only if receipt is available and no error occured
+	if err == nil && receipt != nil {
 		t.ctx = &tracers.Context{
 			BlockHash:   receipt.BlockHash,
 			BlockNumber: receipt.BlockNumber,
 			TxIndex:     int(receipt.TransactionIndex),
 			TxHash:      receipt.TxHash,
 		}
-	if t.interrupt.Load() {
-		return
 	}
 	t.tracer.OnTxEnd(receipt, err)
 }