可以尝试检查输入数据格式是否正确，比如考虑以下代码示例：

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def mergeTrees(t1, t2):
    if t1 is None and t2 is None:
        return None
    if t1 is None:
        return t2
    if t2 is None:
        return t1
    t1.val += t2.val
    t1.left = mergeTrees(t1.left, t2.left)
    t1.right = mergeTrees(t1.right, t2.right)
    return t1

# create binary trees with sample data
t1 = TreeNode(1)
t1.left = TreeNode(3)
t1.right = TreeNode(2)
t1.left.left = TreeNode(5)

t2 = TreeNode(2)
t2.left = TreeNode(1)
t2.right = TreeNode(3)
t2.left.right = TreeNode(4)
t2.right.right = TreeNode(7)

# merge and print result
merged = mergeTrees(t1, t2)
print(merged.val)  # expect 3 (1+2)
print(merged.left.val)  # expect 4 (3+1)
print(merged.right.val)  # expect 5 (2+3)
print(merged.left.right.val)  # expect 4 (4)
print(merged.right.right.val)  # expect 7 (7)

在这个示例中，我们首先定义了一个TreeNode类，以便可以使用对象表示二叉树中的节点。此外，我们定义了一个mergeTrees函数，并按照以下步骤实现：

1. 如果输入的t1和t2都为空，则返回None（合并结束）；
2. 如果t1为空，则返回t2（t2中的节点可以直接加入到t1中）；
3. 如果t2为空，则返回t1（t1中的节点可以直接保留）；
4. 将t