Fix handling of empty choices array in Azure OpenAI API integration

This commit refines the error handling for the Azure OpenAI API
integration to address the 'n.choices[0] is undefined' error by ensuring
'data.choices' and 'data.choices[0]' are properly checked before access.
This update is necessary due to the behavior changes introduced in the
API version update (#684), which can result in empty 'choices' arrays.

Fix #698.

src/services/apis/azure-openai-api.mjs

@@ -47,11 +47,18 @@ export async function generateAnswersWithAzureOpenaiApi(port, question, session)
           console.debug('json error', error)
           return
         }
-        if ('content' in data.choices[0].delta) {
+        if (
+          data.choices &&
+          data.choices.length > 0 &&
+          data.choices[0] &&
+          data.choices[0].delta &&
+          'content' in data.choices[0].delta
+        ) {
           answer += data.choices[0].delta.content
           port.postMessage({ answer: answer, done: false, session: null })
         }
-        if (data.choices[0]?.finish_reason) {
+
+        if (data.choices && data.choices.length > 0 && data.choices[0]?.finish_reason) {
           pushRecord(session, question, answer)
           console.debug('conversation history', { content: session.conversationRecords })
           port.postMessage({ answer: null, done: true, session: session })