fix shutdown while I2P router is initializing

core/src/main/groovy/com/muwire/core/connection/I2PConnector.groovy

@@ -62,10 +62,8 @@ class I2PConnector {
         }
     }
     
-    synchronized void shutdown() {
-        if (socketManager == null)
-            return
-        socketManager.destroySocketManager()
+    void shutdown() {
+        socketManager?.destroySocketManager()
         socketManager = null
     }
 

core/src/main/groovy/com/muwire/core/hostcache/H2HostCache.groovy

@@ -300,8 +300,8 @@ class H2HostCache extends HostCache {
     }
     @Override
     public synchronized void stop() {
-        timer.cancel()
-        sql.close()
+        try {timer.cancel()} catch (Exception ignore) {}
+        sql?.close()
     }
     @Override
     public synchronized void load() {