fixed infinite loop if future result list is empty while checking for finished probes

Author: ic0ns

src/main/java/de/rub/nds/tlsscanner/MultiThreadedScanJobExecutor.java

@@ -170,7 +170,7 @@ private void checkProbesDone(List<Future<ProbeResult>> futureResults, ProgressBa
         boolean isNotReady = true;
         int done = 0;
         int tempDone = 0;
-        while (isNotReady) {
+        while (isNotReady && futureResults.size() > 0) {
             tempDone = 0;
             for (Future<ProbeResult> probeResult : futureResults) {
                 if (probeResult.isDone()) {