Make the assert message more verbose (#6583)

Author: YosuaMichael

torchvision/models/vision_transformer.py

@@ -268,8 +268,8 @@ def __init__(
     def _process_input(self, x: torch.Tensor) -> torch.Tensor:
         n, c, h, w = x.shape
         p = self.patch_size
-        torch._assert(h == self.image_size, "Wrong image height!")
-        torch._assert(w == self.image_size, "Wrong image width!")
+        torch._assert(h == self.image_size, f"Wrong image height, expected {self.image_size} but got {h}!")
+        torch._assert(w == self.image_size, f"Wrong image width, expected {self.image_size} but got {w}!")
         n_h = h // p
         n_w = w // p