Bug 561087: [UnitTest] improve error message on invalid report type

Change-Id: Id4e1dcb9d5436dcbcbcdba65415603edc6710c22

plugins/org.eclipse.ease.lang.unittest/src/org/eclipse/ease/lang/unittest/UnitTestModule.java

diff --git a/plugins/org.eclipse.ease.lang.unittest/src/org/eclipse/ease/lang/unittest/UnitTestModule.java b/plugins/org.eclipse.ease.lang.unittest/src/org/eclipse/ease/lang/unittest/UnitTestModule.java
index 9b0ae4f..fba9d15 100644
--- a/plugins/org.eclipse.ease.lang.unittest/src/org/eclipse/ease/lang/unittest/UnitTestModule.java
+++ b/plugins/org.eclipse.ease.lang.unittest/src/org/eclipse/ease/lang/unittest/UnitTestModule.java
@@ -544,7 +544,7 @@
 			saveDataToFile(reportOutput.getBytes(), fileLocation);
 
 		} else
-			throw new IOException("Report does not contain any data");
+			throw new IllegalArgumentException("Report type \"" + reportType + "\" is unknown");
 	}
 
 	/**