Attribute Error

[efarjun]

Does anyone know why I get and how I can prevent the following error:

"'NoneType' object has no attribute 'replace'

{
"errorMessage": "'NoneType' object has no attribute 'replace'",
"errorType": "AttributeError",
"stackTrace": [
" File "/var/task/main.py", line 38, in lambda_handler\n notifier.send_email(template_values)\n",
" File "/var/task/notifier.py", line 112, in send_email\n self.send_ses_email(template_values)\n",
" File "/var/task/notifier.py", line 119, in send_ses_email\n email_body = self.__render_email_body(template_values)\n",
" File "/var/task/notifier.py", line 95, in __render_email_body\n email = email.replace(placeholder, value)\n"
]
}