text: Title: Surprising empty output in skimage.feature.hog()
  Body: ### Description:
  
  If the image is too small given the chosen `pixels_per_cell` and `cells_per_block`, an empty array is produced as output. [This is a surprising output.](https://stackoverflow.com/q/76681370/7328782)
  
  I suggest you produce a descriptive error message instead.
  
  Alternatively, make this behavior clear in the documentation. The documentation could, by the way, show how to compute the expected output size of the array, as this is not obvious from the outside.
  
  ### Way to reproduce:
  
  ```python
  import numpy as np
  import skimage
  
  img = np.zeros((16, 193))
  print(skimage.feature.hog(img))
  ```
  
  
  ### Version information:
  
  I'm using scikit-image version 0.21.0.
  
  [The remainder of the information is irrelevant, I can see [in the source code where this is happening](https://github.com/scikit-image/scikit-image/blob/76dd2dab856f95e5264f50e376f9f3a81a261287/skimage/feature/_hog.py#L277).]
  