I get a blank assertion error as well

[bhaktatejas922]

I have a similar issue. When doing this I get a blank assertion error as well

`outcome_1, predictors_1 = patsy.dmatrices("Q('%received 18+') ~ n_killed_capita_2016", aggregate_2016_df)

mod_1 = sm.OLS(outcome_1, predictors_1)

res_1 = mod_1.fit()

print(res_1.summary())`

Originally posted by @bhaktatejas922 in https://github.com/pydata/patsy/issues/148#issuecomment-501188532