def error_override_vars(override_vars, spec_filepath):
    """
    Warn user if any given variable name isn't found in the original spec file.
    """
    if override_vars is None:
        return
    original_text = open(spec_filepath, 'r').read()
    for variable in override_vars.keys():
        if variable not in original_text:
            raise ValueError(
                f"Command line override variable '{variable}' not found in spec file '{spec_filepath}'."
                )
