exception handling during mount/unmount/reveal operations

main/commons/src/main/java/org/cryptomator/common/ConsumerThrowingException.java

@@ -0,0 +1,8 @@
+package org.cryptomator.common;
+
+@FunctionalInterface
+public interface ConsumerThrowingException<T, E extends Exception> {
+
+	void accept(T t) throws E;
+
+}

main/commons/src/main/java/org/cryptomator/common/Optionals.java

@@ -0,0 +1,17 @@
+package org.cryptomator.common;
+
+import java.util.Optional;
+
+public final class Optionals {
+
+	private Optionals() {
+	}
+
+	public static <T, E extends Exception> void ifPresent(Optional<T> optional, ConsumerThrowingException<T, E> consumer) throws E {
+		final T t = optional.orElse(null);
+		if (t != null) {
+			consumer.accept(t);
+		}
+	}
+
+}