Prevent crashes if no ttyrec files can be associated with a game.

If the postprocessing step finds no ttyrec files created between a
game's end and the previous game's end, it will no longer index an
empty list and crash.

The condition of finding no ttyrec files is still a bug that requires
investigation.

py/rlgall.py

@@ -226,6 +226,11 @@ class Game:
           lowlim = itsEntries[i-1]["endt"]
         hilim = itsEntries[i]["endt"]
         recs = [ k[1] for k in vfilekeys if lowlim <= k[0] < hilim ]
+        if len(recs) == 0:
+          # There inexplicably are no files.  TODO log an error.
+          itsEntries[i]["startt"] = lowlim
+          itsEntries[i]["ttyrecs"] = []
+        else:
           itsEntries[i]["startt"] = recnameToTS(recs[0])
           itsEntries[i]["ttyrecs"] = recs
     cur.close()