Fix the issues #310 and #309 (#311)

* Fix the issues #310 and #309

Author: abdelkd

Diff for: .changeset/flat-gorillas-happen.md

@@ -0,0 +1,5 @@
+---
+"@google/generative-ai": patch
+---
+
+Fix undefined candidate index.

Diff for: src/requests/stream-reader.ts

@@ -140,34 +140,35 @@ export function aggregateResponses(
   };
   for (const response of responses) {
     if (response.candidates) {
+      let candidateIndex = 0;
       for (const candidate of response.candidates) {
-        const i = candidate.index;
         if (!aggregatedResponse.candidates) {
           aggregatedResponse.candidates = [];
         }
-        if (!aggregatedResponse.candidates[i]) {
-          aggregatedResponse.candidates[i] = {
-            index: candidate.index,
+        if (!aggregatedResponse.candidates[candidateIndex]) {
+          aggregatedResponse.candidates[candidateIndex] = {
+            index: candidateIndex,
           } as GenerateContentCandidate;
         }
         // Keep overwriting, the last one will be final
-        aggregatedResponse.candidates[i].citationMetadata =
+        aggregatedResponse.candidates[candidateIndex].citationMetadata =
           candidate.citationMetadata;
-        aggregatedResponse.candidates[i].groundingMetadata =
+        aggregatedResponse.candidates[candidateIndex].groundingMetadata =
           candidate.groundingMetadata;
-        aggregatedResponse.candidates[i].finishReason = candidate.finishReason;
-        aggregatedResponse.candidates[i].finishMessage =
+        aggregatedResponse.candidates[candidateIndex].finishReason =
+          candidate.finishReason;
+        aggregatedResponse.candidates[candidateIndex].finishMessage =
           candidate.finishMessage;
-        aggregatedResponse.candidates[i].safetyRatings =
+        aggregatedResponse.candidates[candidateIndex].safetyRatings =
           candidate.safetyRatings;
 
         /**
          * Candidates should always have content and parts, but this handles
          * possible malformed responses.
          */
         if (candidate.content && candidate.content.parts) {
-          if (!aggregatedResponse.candidates[i].content) {
-            aggregatedResponse.candidates[i].content = {
+          if (!aggregatedResponse.candidates[candidateIndex].content) {
+            aggregatedResponse.candidates[candidateIndex].content = {
               role: candidate.content.role || "user",
               parts: [],
             };
@@ -189,12 +190,13 @@ export function aggregateResponses(
             if (Object.keys(newPart).length === 0) {
               newPart.text = "";
             }
-            aggregatedResponse.candidates[i].content.parts.push(
+            aggregatedResponse.candidates[candidateIndex].content.parts.push(
               newPart as Part,
             );
           }
         }
       }
+      candidateIndex++;
     }
     if (response.usageMetadata) {
       aggregatedResponse.usageMetadata = response.usageMetadata;