Flutter Gherkin report.json error build

[fadhlimaulidri]

hi, thanks for this library

i use flutter_gherkin, when i build the report.json, i get error

fadhlimaulidri@Fadhlis-MBP bukalapak_seller_apps % report_builder -s test_driver/report/report-ios.json
Traceback (most recent call last):
        10: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/bin/ruby_executable_hooks:24:in `<main>'
         9: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/bin/ruby_executable_hooks:24:in `eval'
         8: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/bin/report_builder:23:in `<main>'
         7: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/bin/report_builder:23:in `load'
         6: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/bin/report_builder:83:in `<top (required)>'
         5: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder.rb:76:in `build_report'
         4: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder/builder.rb:22:in `build_report'
         3: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder/builder.rb:81:in `get_groups'
         2: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder/builder.rb:132:in `get_features'
         1: from /Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder/builder.rb:132:in `each'
/Users/fadhlimaulidri/.rvm/gems/ruby-2.6.5/gems/report_builder-1.9/lib/report_builder/builder.rb:134:in `block in get_features': undefined method `[]' for nil:NilClass (NoMethodError)

this is my report.json

[{"description":"","id":"account page","keyword":"Feature","line":1,"name":"Account page","uri":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/dwi.feature"},{"description":"","id":"seller apps onboarding","keyword":"Feature","line":2,"name":"Seller apps onboarding","uri":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/SEL216.feature","tags":[{"line":1,"name":"@SEL-216"},{"line":1,"name":"@SalesChannel"}],"elements":[{"keyword":"Scenario","type":"scenario","id":"seller apps onboarding;[test] [android] seller app onboarding page - login page","name":"[Test] [Android] Seller App Onboarding Page - Login Page","description":"","line":6,"tags":[{"line":5,"name":"@TEST_SEL-145"},{"line":5,"name":"@SalesChannel"},{"line":5,"name":"@android"},{"line":5,"name":"@ios"},{"line":5,"name":"@manual"},{"line":5,"name":"@seller-app"},{"line":5,"name":"@seller-app-onboarding"}],"steps":[{"keyword":"Given ","name":"there is seller who have been registered before","line":7,"match":{"location":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/SEL216.feature:7"},"result":{"status":"passed","duration":7000000}},{"keyword":"And ","name":"User start selling","line":8,"match":{"location":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/SEL216.feature:8"},"result":{"status":"passed","duration":596000000}},{"keyword":"And ","name":"seller login using valid credential in login page","line":9,"match":{"location":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/SEL216.feature:9"},"result":{"status":"passed","duration":1659000000}}]}]},{"description":"","id":"seller login","keyword":"Feature","line":1,"name":"Seller login","uri":"/Users/fadhlimaulidri/workspace/bukalapak_seller_apps/test_driver/features/example.feature"}]