fix: guard get_language_resources() response and document it (AX-147)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: healqq

README.md

@@ -657,6 +657,25 @@ for language in deepl_client.get_languages_for_resource(
         # Example: "German (de) supports formality"
 ```
 
+#### Listing resources and their features
+
+`get_language_resources()` uses the `/v3/languages/resources` endpoint and
+returns the resources the API offers (translate_text, glossary, write, etc.) as
+a list of `LanguageResourceInfo` objects. Each has `resource` (the name),
+`features` (a map from feature name to `ResourceFeature`) and
+`supports(feature)`. A `ResourceFeature` has `name`, `needs_source_support` and
+`needs_target_support`: `True` means the source (or target) language must
+support the feature for it to be available, `None` means the API did not
+specify it.
+
+```python
+for resource in deepl_client.get_language_resources():
+    for feature in resource.features.values():
+        if feature.needs_target_support:
+            print(f"{resource.resource}: {feature.name} needs target support")
+            # Example: "translate_text: formality needs target support"
+```
+
 #### Listing available glossary languages
 
 Glossaries are supported for a subset of language pairs. To retrieve those

deepl/deepl_client.py

@@ -746,7 +746,8 @@ def get_language_resources(self) -> List[LanguageResourceInfo]:
             "v3/languages/resources", method="GET"
         )
         self._raise_for_status(status, content, json)
-        return [LanguageResourceInfo.from_json(resource) for resource in json]
+        resources = json if (json and isinstance(json, list)) else []
+        return [LanguageResourceInfo.from_json(r) for r in resources]
 
     def get_all_style_rules(
         self,