From 468435e1a02b9dc6979598261e1a4d161b21bdf2 Mon Sep 17 00:00:00 2001
From: Jozufozu <jozsefaug@gmail.com>
Date: Mon, 2 Aug 2021 00:08:26 -0700
Subject: [PATCH] Fix nullpointer when contraptions stop

---
 .../render/ContraptionRenderManager.java       |  9 ++++++++-
 .../render/FlwContraptionManager.java          | 18 +++++++++++-------
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderManager.java b/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderManager.java
index 57d9fa089..8d94a681a 100644
--- a/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderManager.java
+++ b/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/ContraptionRenderManager.java
@@ -50,13 +50,17 @@ public abstract class ContraptionRenderManager<C extends ContraptionRenderInfo>
 	}
 
 	public void beginFrame(BeginFrameEvent event) {
-		visible.clear();
 
 		renderInfos.int2ObjectEntrySet()
 				.stream()
 				.map(Map.Entry::getValue)
 				.forEach(renderInfo -> renderInfo.beginFrame(event));
 
+		collectVisible();
+	}
+
+	protected void collectVisible() {
+		visible.clear();
 		renderInfos.int2ObjectEntrySet()
 				.stream()
 				.map(Map.Entry::getValue)
@@ -80,6 +84,9 @@ public abstract class ContraptionRenderManager<C extends ContraptionRenderInfo>
 		renderInfos.clear();
 	}
 
+	/**
+	 * Remove all render infos associated with dead/removed contraptions.
+	 */
 	public void removeDeadRenderers() {
 		renderInfos.values().removeIf(ContraptionRenderInfo::isDead);
 	}
diff --git a/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/FlwContraptionManager.java b/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/FlwContraptionManager.java
index 8bdb46d9f..3aff78682 100644
--- a/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/FlwContraptionManager.java
+++ b/src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/render/FlwContraptionManager.java
@@ -80,13 +80,17 @@ public class FlwContraptionManager extends ContraptionRenderManager<RenderedCont
 
 	@Override
 	public void removeDeadRenderers() {
-		renderInfos.values().removeIf(renderer -> {
-			if (renderer.isDead()) {
-				renderer.invalidate();
-				return true;
-			}
-			return false;
-		});
+		boolean removed = renderInfos.values()
+				.removeIf(renderer -> {
+					if (renderer.isDead()) {
+						renderer.invalidate();
+						return true;
+					}
+					return false;
+				});
+
+		// we use visible in #tick() so we have to re-evaluate it if any were removed
+		if (removed) collectVisible();
 	}
 
 	@Override