fix(people): resolve type errors (#585)

Resolves TypeScript errors in the `people/quickstart/quickstart.gs` file by:
- Adding JSDoc annotations for `Name`, `Person`, `Connection` and `EmailAddress` types.
- Adding a check to ensure the `People` advanced service is enabled.
- Removing an unhelpful try/catch block.
- Improving the logic to safely access `displayName`.

* docs: Add JSDoc links to People API definitions and clarify partial type definitions.

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: Justin Poehnelt <jpoehnelt@google.com>

Author: google-labs-jules[bot]

people/quickstart/quickstart.gs

@@ -14,31 +14,58 @@
  * limitations under the License.
  */
 // [START people_quickstart]
+/**
+ * @typedef {Object} EmailAddress
+ * @see https://developers.google.com/people/api/rest/v1/people#Person
+ * @property {string} value
+ * Note: This is a partial definition.
+ */
+
+/**
+ * @typedef {Object} Name
+ * @see https://developers.google.com/people/api/rest/v1/people#Person
+ * @property {string} displayName
+ * Note: This is a partial definition.
+ */
+
+/**
+ * @typedef {Object} Person
+ * @see https://developers.google.com/people/api/rest/v1/people#Person
+ * @property {Name[]} names
+ * @property {EmailAddress[]} [emailAddresses]
+ * Note: This is a partial definition.
+ */
+
+/**
+ * @typedef {Object} Connection
+ * @see https://developers.google.com/people/api/rest/v1/people.connections/list
+ * @property {Person[]} connections
+ * Note: This is a partial definition.
+ */
+
 /**
  * Print the display name if available for 10 connections.
  */
 function listConnectionNames() {
-  try {
-    /**
-     * List the 10 connections/contacts of user
-     * @see https://developers.google.com/people/api/rest/v1/people.connections/list
-     */
-    const connections = People.People.Connections.list('people/me', {
-      pageSize: 10,
-      personFields: 'names,emailAddresses'
-      // use other query parameter here if needed.
-    });
-    connections.connections.forEach((person) => {
-      // if contacts/connections is available, print the name of person.
-      if (person.names && person.names.length === 0) {
-        console.log('No display name found for connection.');
-        return;
-      }
-      console.log(person.names[0].displayName);
-    });
-  } catch (err) {
-    // TODO (developer) - Handle exception from People API
-    console.log('Failed with error %s', err.message);
+  // Use the People API to list the connections of the logged in user.
+  // See: https://developers.google.com/people/api/rest/v1/people.connections/list
+  if (!People || !People.People || !People.People.Connections) {
+    throw new Error('People service not enabled.');
   }
+  const connections = People.People.Connections.list('people/me', {
+    pageSize: 10,
+    personFields: 'names,emailAddresses',
+  });
+  if (!connections.connections) {
+    console.log('No connections found.');
+    return;
+  }
+  connections.connections.forEach((person) => {
+    if (person.names && person.names.length > 0 && person.names[0].displayName) {
+      console.log(person.names[0].displayName);
+    } else {
+      console.log('No display name found for connection.');
+    }
+  });
 }
 // [END people_quickstart]