Synchronize hasInvalidBlock predicate, as it wasn't thread safe

src/main/java/org/qortal/controller/Controller.java

@@ -723,6 +723,7 @@ public class Controller extends Thread {
 	};
 
 	public static final Predicate<Peer> hasInvalidBlock = peer -> {
+		synchronized (peer.peerInfoLock) {
 			final PeerChainTipData peerChainTipData = peer.getChainTipData();
 			Map<ByteArray, Long> invalidBlockSignatures = Synchronizer.getInstance().getInvalidBlockSignatures();
 			List<byte[]> peerSignatures = new ArrayList<>();
@@ -756,6 +757,7 @@ public class Controller extends Thread {
 				}
 			}
 			return false;
+		}
 	};
 
 	public static final Predicate<Peer> hasNoRecentBlock = peer -> {

src/main/java/org/qortal/network/Peer.java

@@ -121,7 +121,7 @@ public class Peer {
 
     // Peer info
 
-    private final Object peerInfoLock = new Object();
+    public final Object peerInfoLock = new Object();
 
     private String peersNodeId;
     private byte[] peersPublicKey;