Disallow unsafe type assertions (#18688)

packages/core/src/tools/web-search.ts

@@ -91,6 +91,7 @@ class WebSearchToolInvocation extends BaseToolInvocation<
       const sources = groundingMetadata?.groundingChunks as
         | GroundingChunkItem[]
         | undefined;
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
       const groundingSupports = groundingMetadata?.groundingSupports as
         | GroundingSupportItem[]
         | undefined;