diff --git a/gmail/add-ons/quickstart.gs b/gmail/add-ons/quickstart.gs
index 4afbf310b..448611d15 100644
--- a/gmail/add-ons/quickstart.gs
+++ b/gmail/add-ons/quickstart.gs
@@ -15,14 +15,27 @@
  */
 
 // [START apps_script_gmail_quick_start]
+/**
+ * This is a partial definition of the a Gmail add-on event object.
+ * For the full list of properties, see:
+ * https://developers.google.com/workspace/add-ons/concepts/event-objects
+ *
+ * @typedef {Object} gmailEvent
+ * @property {Object} messageMetadata
+ * @property {string} messageMetadata.accessToken
+ * @property {string} messageMetadata.messageId
+ * @property {Object} formInputs
+ * @property {string[]} formInputs.labels
+ */
+
 /**
  * Returns the array of cards that should be rendered for the current
  * e-mail thread. The name of this function is specified in the
  * manifest 'onTriggerFunction' field, indicating that this function
  * runs every time the add-on is started.
  *
- * @param {Object} e The data provided by the Gmail UI.
- * @return {Card[]}
+ * @param {gmailEvent} e The data provided by the Gmail UI.
+ * @return {CardService.Card[]}
  */
 function buildAddOn(e) {
   // Activate temporary Gmail add-on scopes.
@@ -71,9 +84,9 @@ function buildAddOn(e) {
  * user selections. Runs via the OnChangeAction for
  * each CHECK_BOX created.
  *
- * @param {Object} e The data provided by the Gmail UI.
+ * @param {gmailEvent} e The data provided by the Gmail UI.
 */
-function toggleLabel(e){
+function toggleLabel(e) {
   var selected = e.formInputs.labels;
   
   // Activate temporary Gmail add-on scopes.
@@ -85,30 +98,29 @@ function toggleLabel(e){
   var thread = message.getThread();
   
   if (selected != null){
-     for each (var label in GmailApp.getUserLabels()) {
-       if(selected.indexOf(label.getName()) != -1){
-          thread.addLabel(label);
-       }
-       else {
-         thread.removeLabel(label);
-       }
-     }
-  }
-  else {
-    for each (var label in GmailApp.getUserLabels()) {
+    for (const label of GmailApp.getUserLabels()) {
+      if (selected.indexOf(label.getName()) != -1) {
+        thread.addLabel(label);
+      } else {
+        thread.removeLabel(label);
+      }
+    }
+  } else {
+    for (const label of GmailApp.getUserLabels()) {
       thread.removeLabel(label);
     }
   }
 }
 
+
 /**
- * Converts an GmailLabel object to a array of strings. 
+ * Converts a GmailLabel object to a array of strings.
  * Used for easy sorting and to determine if a value exists.
  *
- * @param {labelsObjects} A GmailLabel object array.
- * @return {lables[]} An array of labels names as strings.
+ * @param {GoogleAppsScript.Gmail.GmailLabel[]} labelsObjects
+ * @return {string[]} An array of labels names as strings.
 */
-function getLabelArray(labelsObjects){
+function getLabelArray(labelsObjects) {
   var labels = [];
   for(var i = 0; i < labelsObjects.length; i++) {
     labels[i] = labelsObjects[i].getName();
diff --git a/gmail/inlineimage/inlineimage.gs b/gmail/inlineimage/inlineimage.gs
index 0ca113c6f..a0050a65e 100644
--- a/gmail/inlineimage/inlineimage.gs
+++ b/gmail/inlineimage/inlineimage.gs
@@ -20,6 +20,9 @@ function sendEmailToMyself() {
   sendEmailWithInlineImage(Session.getActiveUser().getEmail());
 }
 
+/**
+ * @param {string} toAddress
+ */
 function sendEmailWithInlineImage(toAddress) {
   const options = {};
   const imageName = 'cat_emoji';
diff --git a/gmail/markup/Code.gs b/gmail/markup/Code.gs
index d4f65f6ed..4f5587d82 100644
--- a/gmail/markup/Code.gs
+++ b/gmail/markup/Code.gs
@@ -3,17 +3,14 @@
  * Send an email with schemas in order to test email markup.
  */
 function testSchemas() {
-  try {
-    const htmlBody = HtmlService.createHtmlOutputFromFile('mail_template').getContent();
+  const htmlBody =
+      HtmlService.createHtmlOutputFromFile('mail_template').getContent();
 
-    MailApp.sendEmail({
-      to: Session.getActiveUser().getEmail(),
-      subject: 'Test Email markup - ' + new Date(),
-      htmlBody: htmlBody
-    });
-  } catch (err) {
-    console.log(err.message);
-  }
+  MailApp.sendEmail({
+    to: Session.getActiveUser().getEmail(),
+    subject: 'Test Email markup - ' + new Date(),
+    htmlBody: htmlBody,
+  });
 }
 // [END gmail_send_email_with_markup]
 
diff --git a/gmail/quickstart/quickstart.gs b/gmail/quickstart/quickstart.gs
index 51ca6a28c..613bda88b 100644
--- a/gmail/quickstart/quickstart.gs
+++ b/gmail/quickstart/quickstart.gs
@@ -20,22 +20,20 @@
  * @see https://developers.google.com/gmail/api/reference/rest/v1/users.labels/list
  */
 function listLabels() {
-  try {
-    // Gmail.Users.Labels.list() API returns the list of all Labels in user's mailbox
-    const response = Gmail.Users.Labels.list('me');
-    if (!response || response.labels.length === 0) {
-      // TODO (developer) - No labels are returned from the response
-      console.log('No labels found.');
-      return;
-    }
-    // Print the Labels that are available.
-    console.log('Labels:');
-    for (const label of response.labels ) {
-      console.log('- %s', label.name);
-    }
-  } catch (err) {
-    // TODO (developer) - Handle exception on Labels.list() API
-    console.log('Labels.list() API failed with error %s', err.toString());
+  // Add this check to use the Gmail advanced service.
+  if (!Gmail || !Gmail.Users || !Gmail.Users.Labels) {
+    throw new Error('Enable the Gmail Advanced Service.');
+  }
+  // Gmail.Users.Labels.list() API returns the list of all Labels in user's mailbox
+  const response = Gmail.Users.Labels.list('me');
+  if (!response || !response.labels || response.labels.length === 0) {
+    console.log('No labels found.');
+    return;
+  }
+  // Print the Labels that are available.
+  console.log('Labels:');
+  for (const label of response.labels) {
+    console.log('- %s', label.name);
   }
 }
 // [END gmail_quickstart]
diff --git a/gmail/sendingEmails/sendingEmails.gs b/gmail/sendingEmails/sendingEmails.gs
index f8e8e0067..aa5ca3d82 100644
--- a/gmail/sendingEmails/sendingEmails.gs
+++ b/gmail/sendingEmails/sendingEmails.gs
@@ -19,20 +19,16 @@
  * Sends emails with data from the current spreadsheet.
  */
 function sendEmails() {
-  try {
-    const sheet = SpreadsheetApp.getActiveSheet(); // Get the active sheet in spreadsheet
-    const startRow = 2; // First row of data to process
-    const numRows = 2; // Number of rows to process
-    const dataRange = sheet.getRange(startRow, 1, numRows, 2); // Fetch the range of cells A2:B3
-    const data = dataRange.getValues(); // Fetch values for each row in the Range.
-    for (const row of data) {
-      const emailAddress = row[0]; // First column
-      const message = row[1]; // Second column
-      const subject = 'Sending emails from a Spreadsheet';
-      MailApp.sendEmail(emailAddress, subject, message); // Send emails to emailAddresses which are presents in First column
-    }
-  } catch (err) {
-    console.log(err);
+  const sheet = SpreadsheetApp.getActiveSheet();
+  const startRow = 2;
+  const numRows = 2;
+  const dataRange = sheet.getRange(startRow, 1, numRows, 2);
+  const data = dataRange.getValues();
+  for (const row of data) {
+    const emailAddress = row[0];
+    const message = row[1];
+    const subject = 'Sending emails from a Spreadsheet';
+    MailApp.sendEmail(emailAddress, subject, message);
   }
 }
 // [END gmail_send_emails]
@@ -42,29 +38,25 @@ function sendEmails() {
  * Sends non-duplicate emails with data from the current spreadsheet.
  */
 function sendNonDuplicateEmails() {
-  const EMAIL_SENT = 'email sent'; //This constant is used to write the message in Column C of Sheet
-  try {
-    const sheet = SpreadsheetApp.getActiveSheet(); // Get the active sheet in spreadsheet
-    const startRow = 2; // First row of data to process
-    const numRows = 2; // Number of rows to process
-    const dataRange = sheet.getRange(startRow, 1, numRows, 3); // Fetch the range of cells A2:B3
-    const data = dataRange.getValues(); // Fetch values for each row in the Range.
-    for (let i = 0; i < data.length; ++i) {
-      const row = data[i];
-      const emailAddress = row[0]; // First column
-      const message = row[1]; // Second column
-      const emailSent = row[2]; // Third column
-      if (emailSent === EMAIL_SENT) {
-        console.log('Email already sent');
-        return;
-      }
-      const subject = 'Sending emails from a Spreadsheet';
-      MailApp.sendEmail(emailAddress, subject, message);// Send emails to emailAddresses which are presents in First column
-      sheet.getRange(startRow + i, 3).setValue(EMAIL_SENT);
-      SpreadsheetApp.flush(); // Make sure the cell is updated right away in case the script is interrupted
+  const EMAIL_SENT = 'email sent';
+  const sheet = SpreadsheetApp.getActiveSheet();
+  const startRow = 2;
+  const numRows = 2;
+  const dataRange = sheet.getRange(startRow, 1, numRows, 3);
+  const data = dataRange.getValues();
+  for (let i = 0; i < data.length; ++i) {
+    const row = data[i];
+    const emailAddress = row[0];
+    const message = row[1];
+    const emailSent = row[2];
+    if (emailSent === EMAIL_SENT) {
+      console.log('Email already sent');
+      return;
     }
-  } catch (err) {
-    console.log(err);
+    const subject = 'Sending emails from a Spreadsheet';
+    MailApp.sendEmail(emailAddress, subject, message);
+    sheet.getRange(startRow + i, 3).setValue(EMAIL_SENT);
+    SpreadsheetApp.flush();
   }
 }
 // [END gmail_send_non_duplicate_emails]