fix error message

preprocessor/ComputingTasks.cc

@@ -323,7 +323,7 @@ EstimatedParamsStatement::EstimatedParamsStatement(const vector<EstimationParams
       if (dynamic_cast<NumConstNode *>(it->mean)->isNumConstNodeEqualTo(0.5) &&
           dynamic_cast<NumConstNode *>(it->std)->isNumConstNodeEqualTo(0.5))
         {
-          cerr << "The prior density is not defined for the beta distribution when the mean = standard deviation = 0.5." << endl;
+          cerr << "ERROR: The prior density is not defined for the beta distribution when the mean = standard deviation = 0.5." << endl;
           exit(EXIT_FAILURE);
         }
 }