fix: return throwDefaultError as never (#1155)

Author: kuhe

.changeset/polite-beans-call.md

@@ -0,0 +1,2 @@
+---
+---

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/HttpProtocolGeneratorUtils.java

@@ -357,7 +357,7 @@ static Set<StructureShape> generateUnifiedErrorDispatcher(
 
                 // Get the protocol specific error location for retrieving contents.
                 String errorLocation = bodyErrorLocationModifier.apply(context, "parsedBody");
-                writer.openBlock("return throwDefaultError({", "})", () -> {
+                writer.openBlock("return throwDefaultError({", "}) as never", () -> {
                     writer.write("output,");
                     if (errorLocation.equals("parsedBody")) {
                         writer.write("parsedBody,");