title: Use only the variable that caused an if statement to trigger, within the if statement
body: <p>say you have an if statement:</p>
  <pre><code>try {
      if (!a || !b || !c || !d) {
        let nullVariable = ???;
        // use the variable that is null
        throw nullVariable
      }
  } catch (ex) {
    log.debug(`${ex} is not defined`);
  }
  </code></pre>
  <p>Is there a built in way to see which variable was set to null, without creating an if statement for each individual variable?</p>