Stack trace not available when no SLF4J binding in classpath

[sarxos]

When there is no SLF4J binding (e.g. Logback or slf4j-simple) available in the classpath, stack traces from Webcam.getImage() calls in WebcamPanel class are send to /dev/null since ScheduledThreadPoolExecutor does not support UncaughtExceptionHandler and pass all exceptions right back to underlying Future, but because we are passing Runnable instead of Callable we are not able to determine if exception has been thrown.