change Promise<unknown> to Promise<never>

Author: kuhe

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

@@ -332,7 +332,7 @@ static Set<StructureShape> generateUnifiedErrorDispatcher(
         writer.openBlock("const $L = async(\n"
             + "  output: $T,\n"
             + "  context: __SerdeContext,\n"
-            + "): Promise<unknown> => {", "}", errorMethodName, responseType, () -> {
+            + "): Promise<never> => {", "}", errorMethodName, responseType, () -> {
             // Prepare error response for parsing error code. If error code needs to be parsed from response body
             // then we collect body and parse it to JS object, otherwise leave the response body as is.
             if (shouldParseErrorBody) {