A DESCRIPTION OF THE PROBLEM :
When a task within a CompletableFuture encounters an exception and throws a Throwable or Exception object with a faulty 'toString' method, which itself throws another Exception, a cascading failure occurs that causes the CompletableFuture to enter a state where it never completes.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run following code:
public static void main(String[] args) {
            CompletableFuture.supplyAsync(() -> {throw new RuntimeException() { @Override public String getMessage() {throw new IllegalArgumentException("getMessage");}};}).join();
        }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
An error is thrown by the 'CompletableFuture.join()' call, preventing this code from hanging forever.
ACTUAL -
The 'CompletableFuture.join()' call never returns or throws an error.

---------- BEGIN SOURCE ----------
public class Test {
        public static void main(String[] args) {
            var f0 = CompletableFuture.supplyAsync(() -> {
                throw new RuntimeException() {
                    @Override public String getMessage() {
                        throw new IllegalArgumentException("getMessage");
                    }
                };
            });
            var f1 = CompletableFuture.supplyAsync(() -> {
                throw new RuntimeException() {
                    @Override public String toString() {
                        throw new IllegalStateException("toString");
                    }
                };
            });
            // Never completes
            CompletableFuture.anyOf(f0, f1).join();
        }
    }
---------- END SOURCE ----------

FREQUENCY : always