Pattern for Returning *all* the reasons something is invalid

Is there a pattern that helps tell the user at runtime all the reasons their object (or payload) is invalid?

I have an object Foo that, to be valid, needs params a and b to not be null. Unfortunately the parent method that creates it does not guarantee those params will not be null.

I can solve for this with something like the below, but it feels messy and like it won't scale nicely. Is there a better pattern for this?

fun parentMethod(a: String?, b: String?){
  // do stuff
  try {
    val foo = Foo(a, b)
  } catch (e: Exception) {
    LOG.info("Exception when creating a Foo", e.message) // contain *all* error messages
  }
}

class Foo(a: String?, b: String?){
  init {
    val errors = []
    if(a == null){ // How do I tame this?
      errors.push("a cannot be null)
    }
    if(b == null){
      errors.push("b cannot be null")
    }
    if (!errors.isEmpty()) {
      throw InvalidFooException(errors.toString())
    }
  }
}