It would be nice to have ThrowExceptionOnUknownProperties flag in TomlModelOptions class.
Which would instruct the Toml.ToModel operation

Toml.ToModel<MyModel>(str, new TomlModelOptions { IgnoreMissingProperties = true, ThrowExceptionOnUknownProperties = true} )`

to throw exception if it finds unknown(misspelled) properties when de-serializing string into predefined model.