From such an older Flarum version, it's probably a good idea to decide to which version of Flarum you want to try to update first, and update composer.json with an upper limit.
Running composer update without any parameter, or using the --with-all-dependencies or -W flags with any command will attempt to jump to the latest possible Flarum version, which will likely result in incompatible extensions still being installed.
If you just wanted to install nightmode, you should try to do it without the command flag. Why would it be needed?
If you want to jump Flarum version incrementally, you could set "flarum/core": "<0.1.0-beta.14" in composer.json to first jump to Flarum beta 13 for example. Check everything still works there, then set it back to "flarum/core": "^0.1.0" to jump to Flarum beta 16.
I see you don't have many extensions. Another option in this case could be to just create a new Flarum install, import your database, import your asset files, then re-install your extensions. This will avoid having to deal with all the Composer requirement issues.
