[Chainer] ValueError : too many value to unpack (expected 2) エラーの対処法がわかりません

前提・実現したいこと

ここに質問の内容を詳しく書いてください。
（例）PHP(C

発生している問題・エラーメッセージ

PythonでChainerを用いて画像の判別をするプログラムを作っているのですが、プログラムを実行すると ValueError : too many value to unpack (expected 2)　とエラーが出てしまいます。
おそらくnet.pyで行っているデータセットの作り方に問題があるのかと思いますが、対処法がわかりません。

情報が不足しているというご指摘がありましたので、下にエラーメッセージの全文を追加しました。

Exception in main training loop: too many values to unpack (expected 2)
Traceback (most recent call last):
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/trainer.py", line 343, in run
update()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/updaters/standard_updater.py", line 240, in update
self.update_core()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/updaters/standard_updater.py", line 245, in update_core
batch = iterator.next()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/iterators/serial_iterator.py", line 77, in next
batch = [self.dataset[index] for index in indices]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/iterators/serial_iterator.py", line 77, in <listcomp>
batch = [self.dataset[index] for index in indices]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/dataset/dataset_mixin.py", line 67, in getitem
return self.get_example(index)
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/datasets/transform_dataset.py", line 51, in get_example
in_data = self._dataset[i]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/dataset/dataset_mixin.py", line 67, in getitem
return self.get_example(index)
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/datasets/image_dataset.py", line 158, in get_example
path, int_label = self._pairs[i]
Will finalize trainer extensions and updater before reraising the exception.
Traceback (most recent call last):
File "net.py", line 56, in <module>
trainer.run()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/trainer.py", line 376, in run
six.reraise(*exc_info)
File "/usr/lib/python3/dist-packages/six.py", line 703, in reraise
raise value
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/trainer.py", line 343, in run
update()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/updaters/standard_updater.py", line 240, in update
self.update_core()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/training/updaters/standard_updater.py", line 245, in update_core
batch = iterator.next()
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/iterators/serial_iterator.py", line 77, in next
batch = [self.dataset[index] for index in indices]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/iterators/serial_iterator.py", line 77, in <listcomp>
batch = [self.dataset[index] for index in indices]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/dataset/dataset_mixin.py", line 67, in getitem
return self.get_example(index)
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/datasets/transform_dataset.py", line 51, in get_example
in_data = self._dataset[i]
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/dataset/dataset_mixin.py", line 67, in getitem
return self.get_example(index)
File "/home/bigfoot/.local/lib/python3.8/site-packages/chainer/datasets/image_dataset.py", line 158, in get_example
path, int_label = self._pairs[i]
ValueError: too many values to unpack (expected 2)

該当のソースコード

python
---my_chain_model.py---
import chainer
import chainer.functions as F
import chainer.links as L

class MyChain(chainer.Chain):

    def __init__(self):
        super(MyChain,self).__init__()
        with self.init_scope():
            self.conv1 = L.Convolution2D(None,16,5,pad=2)
            self.conv2 = L.Convolution2D(None,32,5,pad=2)
            self.l3 = L.Linear(None,256)
            self.l4 = L.Linear(None,5)

    def __call__(self,x):
        h = F.max_pooling_2d(F.relu(self.conv1(x)),ksize=5,stride=2,pad=2)
        h = F.max_pooling_2d(F.relu(self.conv2(x)),ksize=5,stride=2,pad=2)
        h = F.dropout(F.relu(self.l3(h)))
        y = sef.l4(h)
        return y

---net.py---
import chainer
import glob
from itertools import chain
from chainer.datasets import LabeledImageDataset
from chainer import iterators,training,optimizers,datasets,serializers
from chainer.training import extensions,triggers
from chainer.dataset import concat_examples
import chainer.function as F
import chainer.links as L
from my_chain_model import MyChain

#img-----------

train_path = glob.glob('img/Deers/Deers_train/*')

tr = 0
labels = list()
for index,item in enumerate(train_path):
    labels.append(tr)
    tr = tr+1

train_path_l = list(train_path)

dataset_train = chainer.datasets.LabeledImageDataset(train_path_l,labels)

from chainercv.transforms import resize
from chainer.datasets import TransformDataset

def transform(data):
    img,label = data
    img = resize(img,(500,500))
    return img,label

deerset_train = chainer.datasets.TransformDataset(dataset_train,transform)

#train---------

epoch = 10
batch = 5

model = L.Classifier(MyChain())
optimizer = optimizers.Adam()
optimizer.setup(model)

train_iter = iterators.SerialIterator(deerset_train,batch)
updater = training.StandardUpdater(train_iter,optimizer)
trainer = training.Trainer(updater,(epoch,'epoch'),out='result')

trainer.extend(extensions.dump_graph('main/loss'))
trainer.extend(extensions.snapshot(),trigger=(epoch,'epoch'))
trainer.extend(extensions.LogReport())
trainer.extend(extensions.PrintReport(['epoch','main/loss','main/accuracy']))
trainer.extend(extensions.ProgressBar())
trainer.extend(extensions.PlotReport(['main/loss'],'epoch',file_name='loss.png'))
trainer.extend(extensions.PlotReport(['main/accuracy'],'epoch',file_name='accuracy.png'))
trainer.run()

serializer.save_npz("mymodel.npz",model)