[MINOR] Typo

src/qir/driver/sql/QIRSQLStringVisitor.java

@@ -66,7 +66,7 @@ final class QIRSQLStringVisitor implements IQIRVisitor<String> {
     public final String visit(final QIRGroupBy qirGroup) {
         if (qirGroup.group instanceof QIRLambda)
             return qirGroup.child.accept(this) + " group by " + ((QIRLambda) qirGroup.group).body.accept(this);
-        throw new QIRException("QIR SQL Group not implemented for group type: " + qirGroup.group.getClass());
+        throw new QIRException("QIR SQL GroupBy not implemented for group type: " + qirGroup.group.getClass());
     }
 
     @Override