add malloc memory check in tree_insert()

tree/src/tree.c

@@ -98,6 +98,10 @@ void node_insert(Node* node, int age, char* name) {
 void tree_insert(Tree* tree, int age, char* name) {
     if (tree->root == NULL) {
         Node *node = malloc(sizeof(Node));
+        if (node == NULL) {
+                perror("Failed to allocate memory for new node");
+                exit(EXIT_FAILURE);
+            }
         node->name = name;
         node->left = NULL;
         node->right = NULL;