fix: make example code optional for brick example details endpoint request

[mirkoCrobu]

Motivation

closes #795

Following bricks return 500 when asking for details.

• v1/bricks/arduino:mood_detector
• v1/bricks/arduino:streamlit_ui
• v1/bricks/arduino:vibration_anomaly_detection
• v1/bricks/arduino:video_image_classification
• v1/bricks/arduino:motion_detection
• v1/bricks/arduino:video_object_detection

These specific bricks do not have an associated code example. When details are requested, the system erroneously raises an error because the example is not found, rather than handling the missing data gracefully (by returning an empty field).

Change description

Additional Notes

Reviewer checklist

• PR addresses a single concern.
• PR title and description are properly filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.

[dido18]

I would organize the testdata with the content of the assets folder

Something like

testdata/assets
└── 0.4.8
│      ├── compose
│       │   └── arduino
│       │       ├── arduino_cloud
│       ├── docs
│       │   └── arduino
│       │       ├── arduino_cloud
│       └── examples
│           └── arduino
│               ├── arduino_cloud

[dido18]

Can you give an example of the HTTP response of the BricksDetails endpoint when the brick does not have the examples?
I would like to check the code_examples json field.
and avoid code_exampes:null response

[mirkoCrobu]

@dido18 here a response with no examples

{
  "id": "arduino:mood_detector",
  "name": "Mood Detection",
  "author": "Arduino",
  "description": "This brick analyzes text sentiment to detect the mood expressed.\nIt classifies text as positive, negative, or neutral.\n",
  "category": "text",
  "status": "installed",
  "readme": "# Mood detector brick\n\nThis brick analyzes text sentiment to detect the mood expressed.\nIt classifies text as positive, negative, or neutral.\n\nExamples:\n- \"I love this board!\" -\u003E positive\n- \"The weather is awful\" -\u003E negative\n- \"I am sad today\" -\u003E negative\n- \"The temperature is 25\" -\u003E neutral\n\n## Code example and usage\n\n```python\nfrom arduino.app_bricks.mood_detector import MoodDetector\n\nmood_detection = MoodDetector()\n\n# Output: positive\nprint(mood_detection.get_sentiment(\"this application is nice\"))\n```\n",
  "api_docs_path": "/home/mirkocrobu/.config/arduino-app-cli/assets/0.4.8/api-docs/arduino/app_bricks/mood_detector/API.md",
  "code_examples": [],
  "used_by_apps": null
}