Fix typo in doc and check selector (#437)

Author: hiyuchang

docs/sphinx_doc/source/tutorial/align_with_verl.md

@@ -60,7 +60,7 @@ To match the default training setup of veRL, we set `synchronizer.sync_style=fix
 | `data.max_response_length` | `model.max_response_tokens` | - |
 | `data.filter_overlong_prompts` | `model.enable_prompt_truncation` | Explained later |
 | `data.truncation` | - | Equivalent to `right` |
-| `data.shuffle` | `buffer.explorer_input.taskset.task_selector.selector_type:random` | Taskset-specific |
+| `data.shuffle` | `buffer.explorer_input.taskset.task_selector.selector_type:shuffle` | Taskset-specific |
 
 💡 Detailed explanation:
 

docs/sphinx_doc/source_zh/tutorial/align_with_verl.md

@@ -60,7 +60,7 @@ Trinity-RFT 根据功能将强化微调的大量参数分为几个部分，例
 | `data.max_response_length` | `model.max_response_tokens` | - |
 | `data.filter_overlong_prompts` | `model.enable_prompt_truncation` | 稍后说明 |
 | `data.truncation` | - | 等同于 `right` |
-| `data.shuffle` | `buffer.explorer_input.taskset.task_selector.selector_type:random` | Taskset-specific |
+| `data.shuffle` | `buffer.explorer_input.taskset.task_selector.selector_type:shuffle` | Taskset-specific |
 
 💡 详细说明：
 

trinity/common/config.py

@@ -892,6 +892,8 @@ def _check_interval(self) -> None:
                 )
 
     def _check_explorer_input(self) -> None:
+        from trinity.buffer.selector import SELECTORS
+
         if self.mode in {"train", "serve"}:
             # no need to check explorer_input in serve mode
             return
@@ -932,6 +934,13 @@ def _check_explorer_input(self) -> None:
             set_if_none(taskset.rollout_args, "max_tokens", self.model.max_response_tokens)
             set_if_none(taskset.format, "chat_template", self.model.custom_chat_template)
 
+            # check if selector is supported
+            selector = SELECTORS.get(taskset.task_selector.selector_type)
+            if selector is None:
+                raise ValueError(
+                    f"Selector {taskset.task_selector.selector_type} is not supported."
+                )
+
         for idx, dataset in enumerate(explorer_input.eval_tasksets):
             if not dataset.path:
                 raise ValueError(f"Eval dataset [{dataset}]'s path is not configured.")