Fix IndexOutOfBoundsException in IOExceptionList contructors.

Author: Gary Gregory

src/main/java/org/apache/commons/io/IOExceptionList.java

@@ -52,7 +52,7 @@ public IOExceptionList(final List<? extends Throwable> causeList) {
      * @since 2.9.0
      */
     public IOExceptionList(final String message, final List<? extends Throwable> causeList) {
-        super(message, causeList == null ? null : causeList.get(0));
+        super(message, causeList == null || causeList.isEmpty() ? null : causeList.get(0));
         this.causeList = causeList == null ? Collections.emptyList() : causeList;
     }
 

src/test/java/org/apache/commons/io/IOExceptionListTestCase.java

@@ -49,6 +49,12 @@ public void testCause() {
         assertEquals(list, causeList);
     }
 
+    @Test
+    public void testEmptyList() {
+        new IOExceptionList(Collections.emptyList());
+        new IOExceptionList("foo", Collections.emptyList());
+    }
+
     @Test
     public void testMessageCause() {
         final EOFException cause = new EOFException();