Use bfs_executor only for shard

Author: Totktonada

graphql/impl.lua

@@ -55,12 +55,13 @@ local function gql_execute(qstate, variables, operation_name)
         check(operation_type, 'operation_type', 'string')
         assert(operation_type == 'query' or operation_type == 'mutation',
             'only "query" and "mutation" operation types are supported')
+        local accessor = state.accessor
 
-        if operation_type == 'query' then
+        if operation_type == 'query' and accessor.name == 'shard' then
             return bfs_executor.execute(state.schema, qstate.ast, variables,
                 operation_name, {
                     qcontext = qcontext,
-                    accessor = qstate.state.accessor,
+                    accessor = accessor,
                 })
         else
             local root_value = {}