Fix possible NPE in RiftRegenerator.regenerate()

StevenDimDoors/mod_pocketDim/ticking/RiftRegenerator.java

@@ -57,12 +57,15 @@ public class RiftRegenerator implements IRegularTickReceiver {
 							{
 								dimHelper.getWorld(link.locDimID).setBlockTileEntity(link.locXCoord, link.locYCoord, link.locZCoord, new TileEntityRift());
 							}
+							if (rift != null)
+							{
 								rift.hasGrownRifts = true;
 							}
 						}
 					}
 				}
 			}
+		}
 		catch (Exception e)
 		{
 			System.err.println("An exception occurred in RiftRegenerator.regenerate():");