replace assertion errors and improve error messages

[wyli]

Is your feature request related to a problem? Please describe.
AssertionError such as this case:

MONAI/monai/transforms/compose.py

Lines 223 to 224 in 86c7ecd

	if len(weights) != len(self.transforms):
	raise AssertionError("transforms and weights should be same size if both specified as sequences.")

could be improved to have a more specific type, and the error messages can be more specific about the variables:

if len(weights) != len(self.transforms): 
    raise ValueError(
        f"transforms and weights should be same size, got {len(weights)} and {len(self.transforms)}."
    ) 

[ishandutta0098]

@wyli is this issue still open for more assertion error changes?

[KumoLiu]

Hi @ishandutta0098, yes. Welcome to contribute.