Operators ?:

This is used to access the properties of an object without compile time safety-checks, like the : operator. However, using this operator, if the object is null, the access does not occur, and no runtime error will happen.

var/my_thingy // not assigned to anything, so this will be null
my_thingy?:name = "Damian" // as it is null, no access occurs, and no runtime occurs

var/my_other_thingy = 1 // assigned to a truthy value
my_other_thingy?:name = "Runtime Damian" // as it is not null, access does occur, and 1 does not have a name variable, so a runtime occurs

This behavior is identical to the ?. operator, but that operator will check if the property is valid for the variable's type. As such, that operator is typically preferred, as it will provide compile-time errors.