CQ shared: Fix off-by-nine error leading to lost messages

And `eof` crashes.

The problem is that we may end up trying to read more data
from the file when scanning, despite being at the end of the
file. This results in the current Acc to be returned instead
of the remaining data being parsed.

Author: lhoguin

deps/rabbit/src/rabbit_msg_store.erl

@@ -1599,7 +1599,7 @@ scan_data(<<Size:64, MsgIdInt:128, _Rest/bits>> = Data, Fd, Fun, Offset, FileSiz
     end;
 %% This might be the start of a message.
 scan_data(<<Size:64, Rest/bits>> = Data, Fd, Fun, Offset, FileSize, MsgIdsFound, Acc)
-          when byte_size(Rest) < Size + 1, Size < FileSize - Offset ->
+          when byte_size(Rest) < Size + 1, Size + 9 < FileSize - Offset ->
     scan(Data, Fd, Fun, Offset, FileSize, MsgIdsFound, Acc);
 scan_data(Data, Fd, Fun, Offset, FileSize, MsgIdsFound, Acc)
           when byte_size(Data) < 8 ->