fix(openai-adapters): Add defensive type checks for stream.usage Promise

Added type validation for stream.usage values to prevent NaN:
- Check if promptTokens is a number before using
- Check if completionTokens is a number before using
- Calculate totalTokens from components if not provided
- Default to 0 for any undefined/invalid values

This prevents NaN errors when stream.usage Promise resolves with
unexpected/undefined values in the fallback path.

Co-authored-by: nate <[email protected]>
Generated with [Continue](https://continue.dev)

Author: continue[bot]

packages/openai-adapters/src/apis/Anthropic.ts

@@ -680,12 +680,25 @@ export class AnthropicApi implements BaseLlmApi {
       const finalUsage = await stream.usage;
       if (finalUsage) {
         const { usageChatChunk } = await import("../util.js");
+        const promptTokens =
+          typeof finalUsage.promptTokens === "number"
+            ? finalUsage.promptTokens
+            : 0;
+        const completionTokens =
+          typeof finalUsage.completionTokens === "number"
+            ? finalUsage.completionTokens
+            : 0;
+        const totalTokens =
+          typeof finalUsage.totalTokens === "number"
+            ? finalUsage.totalTokens
+            : promptTokens + completionTokens;
+
         yield usageChatChunk({
           model: body.model,
           usage: {
-            prompt_tokens: finalUsage.promptTokens,
-            completion_tokens: finalUsage.completionTokens,
-            total_tokens: finalUsage.totalTokens,
+            prompt_tokens: promptTokens,
+            completion_tokens: completionTokens,
+            total_tokens: totalTokens,
             prompt_tokens_details: {
               cached_tokens:
                 (finalUsage as any).promptTokensDetails?.cachedTokens ?? 0,

packages/openai-adapters/src/apis/OpenAI.ts

@@ -348,12 +348,25 @@ export class OpenAIApi implements BaseLlmApi {
     if (!hasEmittedUsage) {
       const finalUsage = await stream.usage;
       if (finalUsage) {
+        const promptTokens =
+          typeof finalUsage.promptTokens === "number"
+            ? finalUsage.promptTokens
+            : 0;
+        const completionTokens =
+          typeof finalUsage.completionTokens === "number"
+            ? finalUsage.completionTokens
+            : 0;
+        const totalTokens =
+          typeof finalUsage.totalTokens === "number"
+            ? finalUsage.totalTokens
+            : promptTokens + completionTokens;
+
         yield usageChatChunk({
           model: modifiedBody.model,
           usage: {
-            prompt_tokens: finalUsage.promptTokens,
-            completion_tokens: finalUsage.completionTokens,
-            total_tokens: finalUsage.totalTokens,
+            prompt_tokens: promptTokens,
+            completion_tokens: completionTokens,
+            total_tokens: totalTokens,
           },
         });
       }