add property while parsing, even if it has not been seen before

[tingyeah]

(similar to python behavior)
(this is twong62 from gatech omscs fall 2022)
(this change is for Mac only; if you approve then I can do the same change to the other editions.)

[tingyeah]

To verify, you may try this input file:

home_animal:
    cow (vegan). [if sea_food_fish] [error]
    cat.

sea_food:
    fish. [property sea_food_fish]
    seaweed.

which should generate this output:

Test Case 1  		<error>  (follows [if])
   home_animal :  cow (vegan)


Test Case 2  		(Key = 2.1.)
   home_animal :  cat
   sea_food    :  fish


Test Case 3  		(Key = 2.2.)
   home_animal :  cat
   sea_food    :  seaweed