After investigation, you need to specify the content type in your po file. I replicated your error with the following djangojs.po file:
#: lms/templates/student_account/login.underscore
msgid "Create an Account."
msgstr "Tạo tài khoản"
But this one compiled successfully:
msgid ""
msgstr ""
"Content-Type: text/plain; charset=UTF-8"
#: lms/templates/student_account/login.underscore
msgid "Create an Account."
msgstr "Tạo tài khoản"
I guess we should add that to the docs.