Julia subsetting dataframe with multiple conditions

Question

In DataFramesMeta, why should I wrap every condition within a pair of parentheses? Below is an example dataframe where I want a subset that contains values greater than 1 or is missing.

d = DataFrame(a = [1, 2, missing], b = ["x", "y", missing]);

Using DataFramesMeta to subset:

@chain d begin
    @subset @byrow begin
        (:a > 1) | (:a===missing) 
    end
end

If I don't use parentheses, errors pop up.

@chain d begin
    @subset @byrow begin
        :a > 1 | :a===missing 
    end
end
# ERROR: LoadError: TypeError: non-boolean (Missing) used in boolean context