config should tell give more context when it fails to parse a field, error should include the type

[ankittk]

Hello,

While using go-config, We realized that the error parsing is missing data, what field is giving error if we have tons of config declared in config.go file? If you have a different field and that field fails to parse you get the nested error from same but you have no idea which field in your struct is the one that is failing. This leads to a lot of guessing and lost time.

Example:

RequiredConfig2 int32 `required:"true" env:"REQUIRED_CONFIG_2"`

Error getting:

error loading config | strconv.ParseInt: parsing "test": invalid syntax
main.main.func1()

The error should have mentioned

error loading config | strconv.ParseInt: parsing "test": invalid syntax
main.main.func1() | type=["mystruct"] field="RequiredConfig2"