I triggered this against master, and got the following error:
current directory: /workspace/src/skins/MinervaNeue/skins/MinervaNeue/ruby/2.5.0/gems/json-1.8.3/ext/json/ext/generator /usr/bin/ruby2.5 -r ./siteconf20210422-290-yvozyg.rb extconf.rb creating Makefile current directory: /workspace/src/skins/MinervaNeue/skins/MinervaNeue/ruby/2.5.0/gems/json-1.8.3/ext/json/ext/generator make "DESTDIR=" clean current directory: /workspace/src/skins/MinervaNeue/skins/MinervaNeue/ruby/2.5.0/gems/json-1.8.3/ext/json/ext/generator make "DESTDIR=" compiling generator.c generator.c: In function ‘generate_json’: generator.c:861:25: error: ‘rb_cFixnum’ undeclared (first use in this function); did you mean ‘mFixnum’? } else if (klass == rb_cFixnum) { ^~~~~~~~~~ mFixnum generator.c:861:25: note: each undeclared identifier is reported only once for each function it appears in generator.c:863:25: error: ‘rb_cBignum’ undeclared (first use in this function); did you mean ‘mBignum’? } else if (klass == rb_cBignum) { ^~~~~~~~~~ mBignum make: *** [Makefile:243: generator.o] Error 1 make failed, exit code 2 Gem files will remain installed in /workspace/src/skins/MinervaNeue/skins/MinervaNeue/ruby/2.5.0/gems/json-1.8.3 for inspection. Results logged to /workspace/src/skins/MinervaNeue/skins/MinervaNeue/ruby/2.5.0/extensions/x86_64-linux/2.5.0/json-1.8.3/gem_make.out An error occurred while installing json (1.8.3), and Bundler cannot continue. Make sure that `gem install json -v '1.8.3' --source 'https://rubygems.org/'` succeeds before bundling. In Gemfile: mediawiki_selenium was resolved to 1.7.3, which depends on json
Possibly we need to update mediawiki/selenium?