Validation loss Tensor object is print in progress bar, it is expected only value
🐛 Bug
When I add validation loss in progress bar training, tensor object is printed whereas only loss value is expected.
For example  :
Epoch 1: 100%|██████████| 5/5 [00:04<00:00,  1.21it/s, loss=82.423, v_num=52, val_loss=tensor(76.4331, dtype=torch.float32)]
Validation loss is added with the following command : self.log('val_loss', loss, prog_bar=True)
I tried self.log('val_loss', loss.item(), prog_bar=True) with no effect.
To Reproduce
The bug is reproductible with the minimal code example (https://github.com/PyTorchLightning/pytorch-lightning/blob/master/pl_examples/bug_report_model.py). See code sample below with validation_step overridden :
Code sample
class TestModel(BoringModel):

    def validation_step(self, batch, batch_idx):
        output = self.layer(batch)
        loss = self.loss(batch, output)
        self.log('val_loss', loss, prog_bar=True)
        return {"x": loss}

Expected behavior
It is expected to only obtain value of validation loss in progress bar and not tensor object.
Environment

CUDA:

GPU:
available:         False
version:           None


Packages:

numpy:             1.19.1
pyTorch_debug:     False
pyTorch_version:   1.6.0
pytorch-lightning: 0.10.0
tqdm:              4.50.1


System:

OS:                Darwin
architecture:

64bit



processor:         i386
python:            3.8.6
version:           Darwin Kernel Version 18.7.0: Thu Jun 18 20:50:10 PDT 2020; root:xnu-4903.278.43~1/RELEASE_X86_64