Improve error handling

[carrieedwards]

Is your feature request related to a problem? Please describe.
Currently, errors are defined in various functions, using errors.New() and fmt.Errorf(), and some errors lack details (such as 'bad type' error not specifying the argument that caused the error). Instead, it would be helpful to create custom error types so that common errors can be grouped and appropriate messages can be used when these errors occur.

Describe the solution you'd like
Create an error package with custom error types that can be used across the codebase, with specific details on why the error is occurring.