fix flaky test and improve error handling

just ignore invalid entries

pdb-plotting/src/main/java/org/lucares/recommind/logs/TcpIngestor.java

@@ -93,6 +93,7 @@ public class TcpIngestor implements AutoCloseable {
 					}
 
 					if (entry.isPresent()) {
+						LOGGER.trace("adding entry to queue: {}", entry);
 						queue.put(entry.get());
 					}
 
@@ -169,7 +170,7 @@ public class TcpIngestor implements AutoCloseable {
 					db.put(new BlockingQueueIterator<>(queue, Entry.POISON));
 					finished = true;
 				} catch (final Exception e) {
-					e.printStackTrace();
+					LOGGER.warn("Write to database failed. Will retry with the next element.", e);
 				}
 			}
 			return null;