Async Error Swallowed (ARCH4169)

Key java.logging.future-exception-unhandled · Severity warning · Category logging

Starting a CompletableFuture chain with no error handler lets an async failure vanish silently. The exception is neither logged nor reaches the caller; the failure stays completely invisible.

Incorrect

CompletableFuture.supplyAsync(() -> repository.load(id))
    .thenAccept(cache::put);

Correct

CompletableFuture.supplyAsync(() -> repository.load(id))
    .thenAccept(cache::put)
    .exceptionally(e -> {
        log.error("Async load failed: {}", id, e);
        return null;
    });

Fix

Attach an error handler with exceptionally/handle to every async chain so rejections are logged.