Fix TypeError when API returns null choices (#6313)

* Fix CreateSkillPayloadTool array schema missing items field

The payload parameter's anyOf array variant lacked an items field,
causing Gemini API to reject the tool declaration with 400 Bad Request:
'parameters.properties[payload].any_of[1].items: missing field.'

Add items: {type: object} to the array variant to satisfy the Gemini
API requirement for array type schemas.

Fixes #6279

* Fix TypeError when OpenAI-compatible API returns null choices

Some providers (e.g. OpenRouter) may return a completion where
choices is None rather than an empty list — for instance on rate
limiting, content filtering, or transient errors. The existing code
used len(completion.choices) which throws TypeError on None.

Replace all len(...choices) == 0 checks with 'not ... .choices' which
handles both None and empty list. Affects _query_stream, _parse_openai_completion,
and _extract_reasoning_content.

Fixes #6252

astrbot/core/computer/tools/neo_skills.py

@@ -164,7 +164,7 @@ class CreateSkillPayloadTool(NeoSkillToolBase):
             "type": "object",
             "properties": {
                 "payload": {
-                    "anyOf": [{"type": "object"}, {"type": "array"}],
+                    "anyOf": [{"type": "object"}, {"type": "array", "items": {"type": "object"}}],
                     "description": (
                         "Skill payload JSON. Typical schema: {skill_markdown, inputs, outputs, meta}. "
                         "This only stores content and returns payload_ref; it does not create a candidate or release."

astrbot/core/provider/sources/openai_source.py

@@ -311,7 +311,7 @@ class ProviderOpenAIOfficial(Provider):
                 state.handle_chunk(chunk)
             except Exception as e:
                 logger.warning("Saving chunk state error: " + str(e))
-            if len(chunk.choices) == 0:
+            if not chunk.choices:
                 continue
             delta = chunk.choices[0].delta
             # logger.debug(f"chunk delta: {delta}")
@@ -345,7 +345,7 @@ class ProviderOpenAIOfficial(Provider):
     ) -> str:
         """Extract reasoning content from OpenAI ChatCompletion if available."""
         reasoning_text = ""
-        if len(completion.choices) == 0:
+        if not completion.choices:
             return reasoning_text
         if isinstance(completion, ChatCompletion):
             choice = completion.choices[0]
@@ -468,7 +468,7 @@ class ProviderOpenAIOfficial(Provider):
         """Parse OpenAI ChatCompletion into LLMResponse"""
         llm_response = LLMResponse("assistant")
 
-        if len(completion.choices) == 0:
+        if not completion.choices:
             raise Exception("API 返回的 completion 为空。")
         choice = completion.choices[0]