Inaccurate error message when modifying scale factors

Describe the bug

Setting .scale12, etc. factors to unsupported values raises an inaccurate error message, reporting the supported value and not the specified value.

To Reproduce


In [1]: from openff.toolkit import ForceField

In [2]: sage = ForceField("openff-2.0.0.offxml")
/Users/mattthompson/mambaforge/envs/openff-interchange-env/lib/python3.11/site-packages/smirnoff99frosst/smirnoff99frosst.py:11: UserWarning: Module openff was already imported from None, but /Users/mattthompson/software/openff-toolkit is being added to sys.path
  from pkg_resources import resource_filename

In [3]: sage["vdW"].scale12 = 1 / 3
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:424, in ParameterAttribute._call_converter(self, value, instance)
    422 try:
    423     # Static function.
--> 424     return self._converter(value)
    425 except TypeError:
    426     # Instance method.

TypeError: vdWHandler.scale12() missing 2 required positional arguments: 'attrs' and 'new_scale12'

During handling of the above exception, another exception occurred:

SMIRNOFFSpecError                         Traceback (most recent call last)
Cell In[3], line 1
----> 1 sage["vdW"].scale12 = 1 / 3

File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:1168, in _ParameterAttributeHandler.__setattr__(self, key, value)
   1163         raise MissingIndexedAttributeError(
   1164             f"'{key}' is out of bounds for indexed attribute '{attr_name}'"
   1165         )
   1167 # Forward the request to the next class in the MRO.
-> 1168 super().__setattr__(key, value)

File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:373, in ParameterAttribute.__set__(self, instance, value)
    371 def __set__(self, instance, value):
    372     # Convert and validate the value.
--> 373     value = self._convert_and_validate(instance, value)
    374     setattr(instance, self._name, value)

File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:391, in ParameterAttribute._convert_and_validate(self, instance, value)
    389 value = self._validate_units(value)
    390 # Call the custom converter before setting the value.
--> 391 value = self._call_converter(value, instance)
    392 return value

File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:427, in ParameterAttribute._call_converter(self, value, instance)
    424         return self._converter(value)
    425     except TypeError:
    426         # Instance method.
--> 427         return self._converter(instance, self, value)
    428 return value

File ~/software/openff-toolkit/openff/toolkit/typing/engines/smirnoff/parameters.py:2861, in vdWHandler.scale12(self, attrs, new_scale12)
   2858 @scale12.converter
   2859 def scale12(self, attrs, new_scale12):
   2860     if new_scale12 != 0.0:
-> 2861         raise SMIRNOFFSpecError(
   2862             "Current OFF toolkit is unable to handle scale12 values other than 0.0. "
   2863             "Specified 1-2 scaling was {}".format(self.scale12)
   2864         )
   2865     return new_scale12

SMIRNOFFSpecError: Current OFF toolkit is unable to handle scale12 values other than 0.0. Specified 1-2 scaling was 0.0

In [4]: sage["vdW"].scale14 = 4 / 3

# (no output)

https://github.com/openforcefield/openff-interchange/issues/811

openforcefield / openff-toolkit

Inaccurate error message when modifying scale factors #1725