FIX: an exception cause is itself an exception

lib/turbo_tests.rb

@@ -22,7 +22,7 @@ module TurboTests
         new(
           obj[:backtrace],
           obj[:message],
-          obj[:cause]
+          FakeException.from_obj(obj[:cause])
         )
       end
     end

lib/turbo_tests/json_rows_formatter.rb

@@ -23,7 +23,7 @@ module TurboTests
         {
           backtrace: exception.backtrace,
           message: exception.message,
-          cause: exception.cause
+          cause: exception_to_json(exception.cause)
         }
       end
     end