check_data_frame_throw_error: Validate ml_pipeline_builder transform method returns...
In AlexIoannides/pipeliner: Machine Learning Pipelines for R

Helper function that checks if the object returned from a ml_pipeline_builder method is data.frame (if it isn't NULL), and if it isn't, throws an error that is customised with the returning name.

1	check_data_frame_throw_error(func_return_object, func_name)

`func_return_object`	The object returned from a `ml_pipeline_builder` method.
`func_name`	The name of the function that returned the object.

## Not run: 
transform_method <- function(df) df
data <- data.frame(y = c(1, 2), x = c(0.1, 0.2))
data_transformed <- transform_method(data)
check_data_frame_throw_error(data_transformed, "transform_method")
# NULL

## End(Not run)