fix(js/plugins/google-genai): ignore empty parts in the response (#3482)

Author: pavelgj

js/plugins/google-genai/src/common/converters.ts

@@ -195,7 +195,7 @@ function toGeminiPart(part: Part): GeminiPart {
   if (part.custom) {
     return toGeminiCustom(part);
   }
-  throw new Error('Unsupported Part type' + JSON.stringify(part));
+  throw new Error('Unsupported Part type ' + JSON.stringify(part));
 }
 
 function toGeminiRole(
@@ -424,7 +424,7 @@ function fromGeminiPart(part: GeminiPart, ref: string): Part {
   if (part.executableCode) return fromExecutableCode(part);
   if (part.codeExecutionResult) return fromCodeExecutionResult(part);
 
-  throw new Error('Unsupported GeminiPart type');
+  throw new Error('Unsupported GeminiPart type ' + JSON.stringify(part));
 }
 
 export function fromGeminiCandidate(candidate: GeminiCandidate): CandidateData {
@@ -433,9 +433,10 @@ export function fromGeminiCandidate(candidate: GeminiCandidate): CandidateData {
     index: candidate.index || 0,
     message: {
       role: 'model',
-      content: parts.map((part, index) =>
-        fromGeminiPart(part, index.toString())
-      ),
+      content: parts
+        // the model sometimes returns empty parts, ignore those.
+        .filter((p) => Object.keys(p).length > 0)
+        .map((part, index) => fromGeminiPart(part, index.toString())),
     },
     finishReason: fromGeminiFinishReason(candidate.finishReason),
     finishMessage: candidate.finishMessage,

js/plugins/google-genai/tests/common/converters_test.ts

@@ -679,6 +679,47 @@ describe('fromGeminiCandidate', () => {
         custom: { citationMetadata: undefined, safetyRatings: undefined },
       },
     },
+    {
+      should: 'should ignore empty parts',
+      geminiCandidate: {
+        index: 0,
+        content: {
+          role: 'model',
+          parts: [
+            {}, // this one should be skipped
+            {
+              text: 'Why did the dog go to the bank?\n\nTo get his bones cashed!',
+            },
+          ],
+        },
+        finishReason: 'STOP',
+        safetyRatings: [
+          { category: 'HARM_CATEGORY_HATE_SPEECH', probability: 'NEGLIGIBLE' },
+        ],
+      },
+      expectedOutput: {
+        index: 0,
+        message: {
+          role: 'model',
+          content: [
+            {
+              text: 'Why did the dog go to the bank?\n\nTo get his bones cashed!',
+            },
+          ],
+        },
+        finishReason: 'stop',
+        finishMessage: undefined,
+        custom: {
+          citationMetadata: undefined,
+          safetyRatings: [
+            {
+              category: 'HARM_CATEGORY_HATE_SPEECH',
+              probability: 'NEGLIGIBLE',
+            },
+          ],
+        },
+      },
+    },
   ];
   for (const test of testCases) {
     it(test.should, () => {