resolved spotbugs

Author: Darshan-Baligeri

src/test/java/com/thealgorithms/datastructures/trees/BinaryTreeTest.java

@@ -37,8 +37,11 @@ void test2() {
         t.remove(5);
         t.remove(7);
 
-        Assertions.assertNotNull(t.getRoot(), "Root should not be null after removals.");
-        Assertions.assertEquals(9, t.getRoot().data); // Direct access after ensuring non-null
+        BinaryTree.Node root = t.getRoot();
+        Assertions.assertNotNull(root, "Root should not be null after removals.");
+        if (root != null) { // Additional null check for tool satisfaction
+            Assertions.assertEquals(9, root.data);
+        }
     }
 
     // Test for attempting to remove a nonexistent node