{* ../../docs_src/handling_errors/tutorial002_py39.py hl[14] *}

## Install custom exception handlers { #install-custom-exception-handlers }

You can add custom exception handlers with <a href="https://www.starlette.dev/exceptions/" class="external-link" target="_blank">the same exception utilities from Starlette</a>.

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

@Experimental
public interface VersionRangeResolverResult extends Result<VersionRangeResolverRequest> {

    /**
     * Gets the exceptions that occurred while resolving the version range.
     *
     * @return The list of exceptions that occurred during resolution, never {@code null}
     */
    @Nonnull
    List<Exception> getExceptions();

    /**
     * Gets the versions (in ascending order) that matched the requested range.
     *

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[8,13] *}

### Exceptions auslösen { #raise-exceptions }

Die Abhängigkeiten können Exceptions `raise`n, genau wie normale Abhängigkeiten:

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[10,15] *}

### Rückgabewerte { #return-values }

                    conn.connect();
                    successCount.incrementAndGet();
                } catch (Exception e) {
                    synchronized (exceptions) {
                        exceptions.add(e);
                    }
                    failureCount.incrementAndGet();
                } finally {
                    doneLatch.countDown();
                }

Wenn Sie einen `try`-Block in einer Abhängigkeit mit `yield` verwenden, empfangen Sie alle Exceptions, die bei Verwendung der Abhängigkeit geworfen wurden.

Wenn beispielsweise ein Code irgendwann in der Mitte, in einer anderen Abhängigkeit oder in einer *Pfadoperation*, ein „Rollback“ einer Datenbanktransaktion macht oder eine andere Exception verursacht, empfangen Sie die Exception in Ihrer Abhängigkeit.

    PLATFORM {
      @GwtIncompatible
      @J2ktIncompatible
      @Override
      // returns the types available in "normal" environments
      ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
        return ImmutableMap.of(
            InvocationTargetException.class,
            e -> e instanceof InvocationTargetException,
            StackOverflowError.class,

    PLATFORM {
      @GwtIncompatible
      @J2ktIncompatible
      @Override
      // returns the types available in "normal" environments
      ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
        return ImmutableMap.of(
            InvocationTargetException.class,
            e -> e instanceof InvocationTargetException,
            StackOverflowError.class,

    PLATFORM {
      @GwtIncompatible
      @J2ktIncompatible
      @Override
      // returns the types available in "normal" environments
      ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
        return ImmutableMap.of(
            InvocationTargetException.class,
            e -> e instanceof InvocationTargetException,
            StackOverflowError.class,

    PLATFORM {
      @GwtIncompatible
      @J2ktIncompatible
      @Override
      // returns the types available in "normal" environments
      ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
        return ImmutableMap.of(
            InvocationTargetException.class,
            e -> e instanceof InvocationTargetException,
            StackOverflowError.class,

    PLATFORM {
      @GwtIncompatible
      @J2ktIncompatible
      @Override
      // returns the types available in "normal" environments
      ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
        return ImmutableMap.of(
            InvocationTargetException.class,
            e -> e instanceof InvocationTargetException,
            StackOverflowError.class,