refined error message wrt unexpected type of scheduler

src/storm/modelchecker/prctl/helper/SparseMdpPrctlHelper.cpp

@@ -1277,7 +1277,11 @@ namespace storm {
                 }
                 
                 // Sanity check for created scheduler.
-                STORM_LOG_ASSERT((!produceScheduler && !scheduler) || (!scheduler->isPartialScheduler() && scheduler->isDeterministicScheduler() && scheduler->isMemorylessScheduler()), "Unexpected format of obtained scheduler.");
+                STORM_LOG_ASSERT(!produceScheduler || scheduler, "Expected that a scheduler was obtained.");
+                STORM_LOG_ASSERT((!produceScheduler && !scheduler) || !scheduler->isPartialScheduler(), "Expected a fully defined scheduler");
+                STORM_LOG_ASSERT((!produceScheduler && !scheduler) || !scheduler->isDeterministicScheduler(), "Expected a deterministic scheduler");
+                STORM_LOG_ASSERT((!produceScheduler && !scheduler) || !scheduler->isMemorylessScheduler(), "Expected a memoryless scheduler");
+
 
                 return MDPSparseModelCheckingHelperReturnType<ValueType>(std::move(result), std::move(scheduler));
             }