PrismCL: Error message if -param switch is given but there is no property to check

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@11593 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/prism/PrismCL.java

@@ -242,6 +242,10 @@ public class PrismCL implements PrismModelListener
 		// Sort out properties to check
 		sortProperties();
 
+		if (param && numPropertiesToCheck == 0) {
+			errorAndExit("Parametric model checking requires at least one property to check");
+		}
+
 		// process info about undefined constants
 		try {
 			// first, see which constants are undefined