エラー

 > bundle --version

Traceback (most recent call last):
	2: from /usr/local/opt/ruby/bin/bundle:23:in `<main>'
	1: from /usr/local/Cellar/ruby/2.6.2/lib/ruby/2.6.0/rubygems.rb:302:in `activate_bin_path'
/usr/local/Cellar/ruby/2.6.2/lib/ruby/2.6.0/rubygems.rb:283:in `find_spec_for_exe': Could not find 'bundler' (1.16.2) required by your /Users/makietan/project/makietan/makietan.github.io/Gemfile.lock. (Gem::GemNotFoundException)
To update to the latest version installed on your system, run `bundle update --bundler`.
To install the missing version, run `gem install bundler:1.16.2`

なるほどわからん

入れ直し

デフォルトだと N になるので y をしっかり書く

> gem install bundler

bundler's executable "bundle" conflicts with /usr/local/lib/ruby/gems/2.6.0/bin/bundle
Overwrite the executable? [yN]  y
bundler's executable "bundler" conflicts with /usr/local/lib/ruby/gems/2.6.0/bin/bundler
Overwrite the executable? [yN]  y
Successfully installed bundler-2.0.1
Parsing documentation for bundler-2.0.1
Installing ri documentation for bundler-2.0.1
Done installing documentation for bundler after 3 seconds
1 gem installed

解決

> bundle --version

Bundler version 2.0.1