chore: use optional chaining

Co-authored-by: Dan Hudlow <[email protected]>

packages/ruleset/src/functions/use-date-based-format.js

@@ -232,7 +232,7 @@ function performValidation(schema, path, exampleValue) {
 // parses the object, looking for the value at that path. If it finds one,
 // the value will be returned. If not, the function will return `undefined`.
 function getObjectValueAtPath(obj, pathToValue) {
-  return pathToValue.reduce((value, field) => value[field], obj);
+  return pathToValue.reduce((value, field) => value?.[field], obj);
 }
 
 // "Indirect" examples are those coming from request bodies, response bodies, and parameters.