Fix negative index selecting the first element in sequence functions

json-path/src/main/java/com/jayway/jsonpath/internal/function/sequence/AbstractSequenceAggregation.java

@@ -30,7 +30,7 @@ public Object invoke(String currentPath, PathRef parent, Object model, Evaluatio
                 return objectList.get(targetIndex);
             } else {
                 int realIndex = objectList.size() + targetIndex;
-                if (realIndex > 0) {
+                if (realIndex >= 0) {
                     return objectList.get(realIndex);
                 } else {
                     throw new JsonPathException("Target index:" + targetIndex + " larger than object count:" + objectList.size());

json-path/src/test/java/com/jayway/jsonpath/internal/function/SequenceBoundaryTest.java

@@ -0,0 +1,28 @@
+package com.jayway.jsonpath.internal.function;
+
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.jsonpath.JsonPathException;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class SequenceBoundaryTest {
+    @Test
+    void lastOfSingleton() {
+        Object result = JsonPath.read("[42]", "$.last()");
+        assertThat(result).isEqualTo(42);
+    }
+
+    @Test
+    void negativeIndexCanSelectFirstElement() {
+        Object result = JsonPath.read("[1,2,3]", "$.index(-3)");
+        assertThat(result).isEqualTo(1);
+    }
+
+    @Test
+    void negativeIndexBeforeStartStillFails() {
+        assertThatThrownBy(() -> JsonPath.read("[1,2,3]", "$.index(-4)"))
+            .isInstanceOf(JsonPathException.class);
+    }
+}