[Validator] unclear error message

[hanson-hschang]

Because of the for loop in the __post_init__, it shows the error message but does not show which validation function check that it fails. (I only know one of the methods in the list of self._validate_functions fails.)

Signal-System/src/ss/utility/assertion/validator.py

Lines 36 to 43 in 7f9ad43

	class Validator(metaclass=ValidatorMeta):
	def __init__(self) -> None:
	self._errors: List[str] = []
	self._validate_functions: List[Callable[[], bool]] = []
	def __post_init__(self) -> None:
	for validate in self._validate_functions:
	assert validate(), self._errors

The current error message looks like something as the following:

  File "Signal-System/src/ss/utility/callback.py", line 61, in save
    filepath = FilePathValidator(filename, ".hdf5").get_filepath()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "Signal-System/src/ss/utility/assertion/validator.py", line 32, in __call__
    instance.__post_init__()
  File "Signal-System/src/ss/utility/assertion/validator.py", line 43, in __post_init__
    assert validate(), self._errors
           ^^^^^^^^^^
AssertionError: ['some error message']

It will be better to show more than just validate() has error.

[hanson-hschang]

also maybe add termcolor package?