'NoneType' object has no attribute 'root'

class Bst:
    def __init__(self, val=None):
        self.root = val
        self.left = None
        self.right = None
 
 
def add_in_tree(tree, v):
    if tree.root:
        if tree.root <= v:
            if tree.right is None:
                tree.right = Bst(v)
            else:
                add_in_tree(tree.right, v)
        else:
            if tree.left is None:
                tree.left = Bst(v)
            else:
                add_in_tree(tree.left, v)
    else:
        tree.root = v
 
 
def print_bst(tree, level=0, p="root"):
    print(f"{level * '  '}{p}: val={tree.root}")
    if tree.left:
        print_bst(tree.left, level + 1, "left")
    if tree.right:
        print_bst(tree.right, level + 1, "right")
 
 
def get_min(tree):
    if tree.left is None:
        return tree.root
    return get_min(tree.left)
 
 
def find_val(tree, key):
    if tree is None:
        return False
    if tree.root == key:
        return True
 
    res1 = find_val(tree.left, key)
    if res1:
        return True
    res2 = find_val(tree.right, key)
 
    return res2
 
 
def parent_search(tree, child_node):
    if tree.root:
        if tree.left and tree.left.root == child_node:
            return tree.root
        if tree.right and tree.right.root == child_node:
            return tree.root
        elif tree.root:
            return parent_search(tree.left, child_node) or parent_search(tree.right, child_node)
 
 
arr = [6, 8, -1, 3, 0, 5, 2, 11, 4]
bt = Bst()
for a in arr:
    add_in_tree(bt, a)
print_bst(bt)
print()
print(f"min value in the bst1:", get_min(bt))
num = 12
print(f"value {num} is exist:", find_val(bt, num))
 
 
child = 3
print(f"the parent of node {child} is: ", parent_search(bt, child))

class TreeNode:
    def __init__(self, value):
        self.val = value
        self.left = None
        self.right = None
 
 
def insert(node, key):
    if node is None:
        return TreeNode(key)
    else:
        if node.val == key:
            return node
        elif node.val < key:
            node.right = insert(node.right, key)
        else:
            node.left = insert(node.left, key)
    return node
 
 
def preorder(rt):
    if rt is None:
        return
    else:
        preorder(rt.left)
        print(rt.val, end=' ')
        preorder(rt.right)
 
 
def parent_search(tree, child_node):
    if tree:
        if tree.left and tree.left.val == child_node:
            return tree.val
        if tree.right and tree.right.val == child_node:
            return tree.val
        elif tree.val:
            return parent_search(tree.left, child_node) or parent_search(tree.right, child_node)
 
 
if __name__ == '__main__':
    arr = [6, 8, -1, 3, 0, 5, 2, 11, 4]
    bt = TreeNode(arr[0])
    for a in arr:
        insert(bt, a)
    preorder(bt)
    print()
    a1, a2 = [], []
    for i in arr:
        b = parent_search(bt, i)
        a1.append(b)
        a2.append(i)
    a3 =[list(tup) for tup in zip(a1, a2)]
    print(a3)
    print(f"child =2, parent = {parent_search(bt, 2)}") # child =2, parent = None