Fix NPE in FluidFlowLogging

Fixes #724

src/main/java/de/diddiz/LogBlock/listeners/FluidFlowLogging.java

@@ -39,6 +39,7 @@ public class FluidFlowLogging extends LoggingListener {
             }
             if (typeFrom == Material.SEAGRASS || typeFrom == Material.KELP_PLANT || typeFrom == Material.KELP) {
                 typeFrom = Material.WATER;
+                fromWaterlogged = true;
             } 
 
             Block source = Config.logFluidFlowAsPlayerWhoTriggeredIt ? event.getBlock() : null;