Fixed error.

tasksetgen.py

@@ -55,11 +55,14 @@ def lcm(a, b):
     return (a * b) / gcd(a, b)
 
 def hyperperiod(tasks):
-    periods = [task.period for task in tasks]
-    hyperperiod = periods[0]
-    for period in periods[1:]:
-        hyperperiod = lcm(hyperperiod, period)
-    return hyperperiod
+    try:
+        periods = [task.period for task in tasks]
+        hyperperiod = periods[0]
+        for period in periods[1:]:
+            hyperperiod = lcm(hyperperiod, period)
+        return hyperperiod
+    except IndexError:
+        return 0
 
 class Timebase(Enum):
     seconds = 1