validateChatHistory is now checking that 'parts' property is an array (…

…#62)

* validateChatHistory is now checking that 'parts' property is an array

* typo

.changeset/lazy-houses-attend.md

@@ -0,0 +1,5 @@
+---
+"@google/generative-ai": patch
+---
+
+validateChatHistory is now checking that 'parts' property is an array

packages/main/src/methods/chat-session-helpers.test.ts

@@ -102,6 +102,16 @@ describe("chat-session-helpers", () => {
         ],
         isValid: true,
       },
+      {
+        //@ts-expect-error
+        history: [{ role: "user", parts: "" }],
+        isValid: false,
+      },
+      {
+        //@ts-expect-error
+        history: [{ role: "user" }],
+        isValid: false,
+      },
       {
         history: [{ role: "user", parts: [] }],
         isValid: false,

packages/main/src/methods/chat-session-helpers.ts

@@ -56,6 +56,12 @@ export function validateChatHistory(history: Content[]): void {
       );
     }
 
+    if (!Array.isArray(parts)) {
+      throw new GoogleGenerativeAIError(
+        "Content should have 'parts' property with an array of Parts",
+      );
+    }
+
     if (parts.length === 0) {
       throw new GoogleGenerativeAIError(
         "Each Content should have at least one part",
@@ -89,7 +95,11 @@ export function validateChatHistory(history: Content[]): void {
       const validPreviousContentRoles = VALID_PREVIOUS_CONTENT_ROLES[role];
       if (!validPreviousContentRoles.includes(prevContent.role)) {
         throw new GoogleGenerativeAIError(
-          `Content with role '${role}' can't follow '${prevContent.role}'`,
+          `Content with role '${role}' can't follow '${
+            prevContent.role
+          }'. Valid previous roles: ${JSON.stringify(
+            VALID_PREVIOUS_CONTENT_ROLES,
+          )}`,
         );
       }
     }