Profile Lookup - IF not true if ELSE present

I’m afraid I don’t understand something related to this challenge.

This IF statement renders true, and returns half of the challenge as correct.

for (i = 0; i < contacts.length; i++){
    if (contacts[i].firstName === firstName &&  contacts[i].hasOwnProperty(prop)){
      return contacts[i][prop];
    }
  }

BUT, when I add an ELSE statement, the first half is not true anymore

  for (i = 0; i < contacts.length; i++){
    if (contacts[i].firstName === firstName &&  contacts[i].hasOwnProperty(prop)){
      return contacts[i][prop];
    }else {
      return "whatever";
    }
  }

So my question, if an If statement is once seen as TRUE, how can an Else statement render it FALSE?