Fix trying to roll a zero-sided die error

modules/Dice.py

@@ -119,6 +119,12 @@ class Dice(Module):
                     size = m[1]
                     if keep > dice or keep == 0:
                         keep = dice
+                    if size < 1:
+                        output = "# of sides for die is incorrect: %d" % size
+                        return output
+                    if dice < 1:
+                        output = "# of dice is incorrect: %d" % dice
+                        return output
                     res = self.roll_dice(keep, dice, size)
                     curr_str += "%d%s" % (res[0], res[1])
                     res = res[0]