fix: resolve html invalid nesting, english routing 404s, and nodemailer missing credentials

payload.config.ts

@@ -86,10 +86,14 @@ export default buildConfig({
         transportOptions: {
           host: process.env.MAIL_HOST || 'smtp.eu.mailgun.org',
           port: Number(process.env.MAIL_PORT) || 587,
-          auth: {
-            user: process.env.MAIL_USERNAME,
-            pass: process.env.MAIL_PASSWORD,
-          },
+          ...(process.env.MAIL_USERNAME
+            ? {
+                auth: {
+                  user: process.env.MAIL_USERNAME,
+                  pass: process.env.MAIL_PASSWORD,
+                },
+              }
+            : {}),
         },
       })
     : undefined,