[ExpressionLanguage] Null-Coalescing operator supporting non-existent data about symfony-docs HOT 3 CLOSED

To be exact, the if it exists part is true when accessing potentially-missing array keys. But accessing a non-existent variable won't be allowed even with this operator (side note: this is also the way this operator works in JS, where a ?? 'fallback' will still throw a ReferenceError if the variable a does not exist)

from symfony-docs.

@stof It specifically calls out "like PHP null-coalescing", where $never_defined ?? 'fallback' is perfectly valid thing.

from symfony-docs.

Yeah, this part should be updated. I'm not saying that the doc is correct right now. But the part saying if it exists must not be removed entirely either.

from symfony-docs.