Better error message for unexpected non-exception.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@4641 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/parser/ast/Property.java

@@ -199,8 +199,7 @@ public class Property extends ASTElement
 				return true;
 			}
 			throw new PrismException("Unexpected error: " + errMsg);
-		}
-		if (strExpected.startsWith("Error")) {
+		} else if (strExpected.startsWith("Error")) {
 			throw new PrismException("Was expecting an error");
 		}