fix(gguf): correct mismatched-shape error message in check_quantized_param_shape (#13504)

fix(gguf): correct mismatched-shape error message

check_quantized_param_shape compares inferred_shape against
current_param_shape, but the error message printed inferred_shape
vs loaded_param_shape — and inferred_shape is derived from
loaded_param_shape, so the reported mismatch was effectively
self-referential and gave no signal about the model's expected shape.

Print current_param_shape (what the model expected) vs inferred_shape
(what the quantized weight decodes to) so the two sides of the
comparison are actually visible.

Noted by @Vargol in #13001.

Author: Ricardo-M-L

src/diffusers/quantizers/gguf/gguf_quantizer.py

@@ -85,7 +85,8 @@ def check_quantized_param_shape(self, param_name, current_param, loaded_param):
         inferred_shape = _quant_shape_from_byte_shape(loaded_param_shape, type_size, block_size)
         if inferred_shape != current_param_shape:
             raise ValueError(
-                f"{param_name} has an expected quantized shape of: {inferred_shape}, but received shape: {loaded_param_shape}"
+                f"{param_name} has an expected shape of: {current_param_shape}, but the loaded GGUF weight decodes "
+                f"to shape: {inferred_shape}"
             )
 
         return True