No-op remove() on orphan nodes

As suggested in #1898

CHANGES

@@ -1,6 +1,9 @@
 jsoup changelog
 
 Release 1.16.1 [PENDING]
+  * Improvement: Calling Node.remove() on a node with no parent is now a no-op, vs a validation error.
+    <https://github.com/jhy/jsoup/issues/1898>
+
   * Bugfix: Corrected support for ruby elements (<ruby>, <rp>, <rt>, and <rtc>) to current spec.
     <https://github.com/jhy/jsoup/issues/1294>
 

src/main/java/org/jsoup/nodes/Node.java

@@ -315,11 +315,12 @@ public Node root() {
     }
 
     /**
-     * Remove (delete) this node from the DOM tree. If this node has children, they are also removed.
+     * Remove (delete) this node from the DOM tree. If this node has children, they are also removed. If this node is
+     * an orphan, nothing happens.
      */
     public void remove() {
-        Validate.notNull(parentNode);
-        parentNode.removeChild(this);
+        if (parentNode != null)
+            parentNode.removeChild(this);
     }
 
     /**

src/test/java/org/jsoup/nodes/NodeTest.java

@@ -157,6 +157,14 @@ public void handlesAbsOnProtocolessAbsoluteUris() {
         assertEquals("<span>two</span> three", TextUtil.stripNewlines(p.html()));
     }
 
+    @Test void removeOnOrphanIsNoop() {
+        // https://github.com/jhy/jsoup/issues/1898
+        Element node = new Element("div");
+        assertNull(node.parentNode());
+        node.remove();
+        assertNull(node.parentNode());
+    }
+
     @Test public void testReplace() {
         Document doc = Jsoup.parse("<p>One <span>two</span> three</p>");
         Element p = doc.select("p").first();