An error occurred while installing json (2.1.0), and Bundler cannot continue.

[agordeev]

I ran fastlane add_plugin appicon and got this result:

[20:27:54]: fastlane detected a Gemfile in the current directory
[20:27:54]: however it seems like you don't use `bundle exec`
[20:27:54]: to launch fastlane faster, please use
[20:27:54]: 
[20:27:54]: $ bundle exec fastlane add_plugin appicon
[20:27:54]: 
[20:27:54]: Get started using a Gemfile for fastlane https://docs.fastlane.tools/getting-started/ios/setup/#use-a-gemfile
[20:27:56]: Plugin 'fastlane-plugin-appicon' was added to './fastlane/Pluginfile'
[20:27:56]: Make sure to commit your Gemfile, Gemfile.lock and Pluginfile to version control
Installing plugin dependencies...
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/andreygordeev/.fastlane/bin/bundle/lib/ruby/gems/2.2.0/gems/json-2.1.0/ext/json/ext/generator
/Users/andreygordeev/.fastlane/bin/bundle/bin/ruby -r ./siteconf20180128-83207-1711sfk.rb extconf.rb
creating Makefile

current directory: /Users/andreygordeev/.fastlane/bin/bundle/lib/ruby/gems/2.2.0/gems/json-2.1.0/ext/json/ext/generator
make "DESTDIR=" clean

current directory: /Users/andreygordeev/.fastlane/bin/bundle/lib/ruby/gems/2.2.0/gems/json-2.1.0/ext/json/ext/generator
make "DESTDIR="
compiling generator.c
clang: warning: no such sysroot directory: '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk' [-Wmissing-sysroot]
In file included from generator.c:1:
In file included from ./../fbuffer/fbuffer.h:5:
In file included from /Users/andreygordeev/.fastlane/bin/bundle/include/ruby-2.2.0/ruby.h:33:
In file included from /Users/andreygordeev/.fastlane/bin/bundle/include/ruby-2.2.0/ruby/ruby.h:29:
/Users/andreygordeev/.fastlane/bin/bundle/include/ruby-2.2.0/ruby/defines.h:26:10: fatal error: 'stdio.h' file not found
#include <stdio.h>
         ^~~~~~~~~
1 error generated.
make: *** [generator.o] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/andreygordeev/.fastlane/bin/bundle/lib/ruby/gems/2.2.0/gems/json-2.1.0 for inspection.
Results logged to /Users/andreygordeev/.fastlane/bin/bundle/lib/ruby/gems/2.2.0/extensions/x86_64-darwin-15/2.2.0-static/json-2.1.0/gem_make.out

An error occurred while installing json (2.1.0), and Bundler cannot continue.
Make sure that `gem install json -v '2.1.0'` succeeds before bundling.

I executed sudo gem install json -v '2.1.0' and reran the command, but got the same result