handle empty case with ncOutgoingQueue

1 files changed, 5 insertions, 1 deletions

diff --git a/src/Data/PacketQueue.hs b/src/Data/PacketQueue.hs
index 144c8de0..4770d4a9 100644
--- a/src/Data/PacketQueue.hs
+++ b/src/Data/PacketQueue.hs
@@ -193,7 +193,11 @@ tryAppendQueueOutgoing :: STM extra -> PacketOutQueue extra msg wire fromwire ->
 tryAppendQueueOutgoing getExtra q@(PacketOutQueue { pktoInPQ, pktoOutPQ, pktoPacketNo, pktoToWireIO, pktoToWire }) msg = do
     be <- readTVar (buffend pktoOutPQ)
     let i = be `mod` (qsize pktoOutPQ)
-    mbPkt <- readArray (pktq pktoOutPQ) i
+    let arrayEmpty ar = do (lowB,highB) <- getBounds ar
+                           return (lowB > highB )
+    mbPkt <- do emp <- arrayEmpty (pktq pktoOutPQ)
+                if emp then return Nothing
+                       else readArray (pktq pktoOutPQ) i
     pktno <- readTVar pktoPacketNo
     nextno <- readTVar (seqno pktoInPQ)
     mbWire <- pktoToWire getExtra nextno be pktno msg