static ServerErrorHandler ofDefault() {
        return DefaultServerErrorHandler.INSTANCE;
    }
Returns the default {@link ServerErrorHandler}. This handler is also used as the final fallback when
the handler customized with {@link ServerBuilder#errorHandler(ServerErrorHandler)} returns {@code null}.
For example, the following handler basically delegates all error handling to the default handler:
<pre>{@code
Server
  .builder()
  .errorHandler((ctx, cause) -> null)
  ...
}</pre>
core/src/main/java/com/linecorp/armeria/server/ServerErrorHandler.java