Reverted exception in ArrayIndexFilter and fixed tests.

json-path/src/main/java/com/jayway/jsonpath/internal/filter/ArrayIndexFilter.java

@@ -97,7 +97,8 @@ public class ArrayIndexFilter extends PathTokenFilter {
             String[] indexArr = COMMA.split(trimmedCondition);
 
             if(obj == null || jsonProvider.length(obj) == 0){
-                throw new PathNotFoundException("Failed to access array index: '" + condition + "' since the array is null or empty");
+                //throw new PathNotFoundException("Failed to access array index: '" + condition + "' since the array is null or empty");
+                return result;
             }
 
             if (indexArr.length == 1) {

json-path/src/test/java/com/jayway/jsonpath/IssuesTest.java

@@ -23,7 +23,8 @@ import static org.junit.Assert.assertThat;
  */
 public class IssuesTest {
 
-    @Test
+    //@Test(expected = PathNotFoundException.class)
+    @Test()
     public void issue_11() throws Exception {
         String json = "{ \"foo\" : [] }";
         List<String> result = JsonPath.read(json, "$.foo[?(@.rel= 'item')][0].uri");