https://choosealicense.com/licenses/mit/
I see license MIT on this site, but I do not see any license on your GitHub repository.

How to apply this license (common)
Create a text file (typically named LICENSE or LICENSE.txt) in the root of your source code and copy the text of the license into the file. Replace [year] with the current year and [fullname] with the name (or names) of the copyright holders.

Unlicenced code on GitHub has implicit All Rights Reserved, except rights to view and fork repository on GitHub. So I guess if you started with zipped mod downloaded from mod portal, you can do lots of stuff (according to MIT), but if you started with GitHub code you afaik cannot distribute any derivative (e.g. a new mod) or even reuse pieces of code. Very strange combination, probably not intended by the author but it is what it is.

Also, there is a very important part. If I want to create/modificate using another mod but the mod doesn't have any license (?!) in its project, then I can't correctly write a license, because I miss important data of condition license in the current situation.

If there are several authors/contributors, then need more spend attention...

For example:

https://github.com/nea/Typescript-Starter/issues/1
https://github.com/GoogleCloudPlatform/google-cloud-gemserver/issues/36
https://github.com/BenSibley/Author/blob/master/licenses.txt
https://github.com/spf13/cobra/issues/247 xD
https://github.com/salesforce/gorp/issues/2
https://github.com/oxygenxml/dim/blob/master/info-model/rules/styleguide/webhelp/license-3rd-party.txt