homebrew

1. 执行命令失败
   Version value must be a string; got a NilClass

Traceback(most recent call last):

11: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `'

10: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `require_relative'

9: from /usr/local/Homebrew/Library/Homebrew/global.rb:29:in `'

8: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'

7: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'

6: from /usr/local/Homebrew/Library/Homebrew/os.rb:3:in `'

5: from /usr/local/Homebrew/Library/Homebrew/os.rb:21:in `'

4: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:58:in `prerelease?'

3: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:24:in `version'

2: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:24:in `new'

1: from /usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:26:in `initialize'

/usr/local/Homebrew/Library/Homebrew/version.rb:368:in `initialize':Version value must be a string; got a NilClass () (TypeError)

解决方法：

brew update-reset