model_reactive.R

# Create a linear model
  model_reactive <- metaReactive2({
    validate(need(is.data.frame(data_set_reactive()), "Data Set could not be created"))
    validate(need(is.language(formula_reactive()), "Formula could not be created from column selections"))

    metaExpr(bindToReturn = TRUE, {
      model_data <- !!data_set_reactive()
      lm(formula = !!formula_reactive(), data = model_data)
    })
  })