Repository: facebookresearch/ParlAI

Issue:
FileNotFoundError when running WoW in interactive
**Bug description**
I am running the following command: `parlai interactive -mf models:wizard_of_wikipedia/end2end_generator/model -t wizard_of_wikipedia`. At the step when "loading topics" there is a missing file error: `FileNotFoundError: [Errno 2] No such file or directory: '/mnt/disks/disk-huge/melody/parlai/data/wizard_of_wikipedia/topic_splits.json'`

**Reproduction steps**
Run `parlai interactive -mf models:wizard_of_wikipedia/end2end_generator/model -t wizard_of_wikipedia`

**Expected behavior**
The file is automatically downloaded, topics are loaded and the interactive session begins.

**Logs**
Please paste the command line output:

```
14:49:06 | creating task(s): wizard_of_wikipedia
[ loading topics.. ]
Traceback (most recent call last):
  File "/home/melody/anaconda3/envs/parlai/bin/parlai", line 33, in <module>
    sys.exit(load_entry_point('parlai', 'console_scripts', 'parlai')())
  File "/mnt/disks/disk-huge/melody/parlai/parlai/core/script.py", line 272, in superscript_main
    SCRIPT_REGISTRY[cmd].klass._run_from_parser_and_opt(opt, parser)
  File "/mnt/disks/disk-huge/melody/parlai/parlai/core/script.py", line 88, in _run_from_parser_and_opt
    return script.run()
  File "/mnt/disks/disk-huge/melody/parlai/parlai/scripts/interactive.py", line 117, in run
    return interactive(self.opt)
  File "/mnt/disks/disk-huge/melody/parlai/parlai/scripts/interactive.py", line 88, in interactive
    world = create_task(opt, [human_agent, agent])
  File "/mnt/disks/disk-huge/melody/parlai/parlai/core/worlds.py", line 1262, in create_task
    world = create_task_world(opt, user_agents, default_world=default_world)
  File "/mnt/disks/disk-huge/melody/parlai/parlai/core/worlds.py", line 1235, in create_task_world
    return world_class(opt, task_agents + user_agents)
  File "/mnt/disks/disk-huge/melody/parlai/parlai/tasks/wizard_of_wikipedia/worlds.py", line 53, in __init__
    self._load_topics(opt)
  File "/mnt/disks/disk-huge/melody/parlai/parlai/tasks/wizard_of_wikipedia/worlds.py", line 82, in _load_topics
    self.topic_list = json.load(open(topics_path, 'rb'))[datatype]
FileNotFoundError: [Errno 2] No such file or directory: '/mnt/disks/disk-huge/melody/parlai/data/wizard_of_wikipedia/topic_splits.json'
```

**Additional context**
Add any other context about the problem here. (like proxy settings, network setup, overall goals, etc.)



Discussion:

Resolving patch:
diff --git a/parlai/tasks/wizard_of_wikipedia/worlds.py b/parlai/tasks/wizard_of_wikipedia/worlds.py
--- a/parlai/tasks/wizard_of_wikipedia/worlds.py
+++ b/parlai/tasks/wizard_of_wikipedia/worlds.py
@@ -18,6 +18,8 @@
 from parlai.tasks.self_chat.worlds import SelfChatWorld as SelfChatBaseWorld
 from parlai.utils.misc import warn_once
 
+from .build import build
+
 from projects.wizard_of_wikipedia.knowledge_retriever.knowledge_retriever import (
     KnowledgeRetrieverAgent,
 )
@@ -74,6 +76,7 @@ def _set_up_knowledge_agent(self, add_token_knowledge=False):
 
     def _load_topics(self, opt):
         # Load possible chosen topics
+        build(opt)
         topics_path = os.path.join(
             opt['datapath'], 'wizard_of_wikipedia', 'topic_splits.json'
         )


Test patch: