Fix crash on load when backend is off

- Closes #81
 - Disabled crashing on error poll

src/main/java/com/jozufozu/flywheel/backend/gl/buffer/PersistentGlBuffer.java

@@ -12,7 +12,6 @@ import com.jozufozu.flywheel.backend.Backend;
 import com.jozufozu.flywheel.backend.gl.GlFence;
 import com.jozufozu.flywheel.backend.gl.error.GlError;
 import com.jozufozu.flywheel.backend.gl.error.GlException;
-import com.jozufozu.flywheel.util.StringUtil;
 
 public class PersistentGlBuffer extends GlBuffer implements Mappable {
 
@@ -49,13 +48,6 @@ public class PersistentGlBuffer extends GlBuffer implements Mappable {
 
 		Backend.getInstance().compat.bufferStorage.bufferStorage(type, size, flags);
 
-		GlError error = GlError.poll();
-		if (error != null) {
-			// If this error is being thrown but everything seems fine,
-			// GlError.poll() might be returning an error from something earlier.
-			throw new GlException(error, StringUtil.args("bufferStorage", type, size, flags));
-		}
-
 		ByteBuffer byteBuffer = GL30.glMapBufferRange(type.glEnum, 0, size, flags);
 
 		if (byteBuffer == null) {

src/main/java/com/jozufozu/flywheel/backend/gl/error/GlError.java

@@ -5,8 +5,6 @@ import java.util.function.Supplier;
 import org.lwjgl.opengl.GL20;
 import org.lwjgl.opengl.GL30;
 
-import com.jozufozu.flywheel.Flywheel;
-
 import it.unimi.dsi.fastutil.ints.Int2ObjectArrayMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 
@@ -41,10 +39,10 @@ public enum GlError {
 	}
 
 	public static void pollAndThrow(Supplier<String> context) {
-		// TODO: build flag? to enable or disable this function
-		GlError err = GlError.poll();
-		if (err != null) {
-			Flywheel.LOGGER.error("{}: {}", err.name(), context.get());
-		}
+// 		This was a bad idea.
+//		GlError err = GlError.poll();
+//		if (err != null) {
+//			Flywheel.LOGGER.error("{}: {}", err.name(), context.get());
+//		}
 	}
 }

src/main/java/com/jozufozu/flywheel/backend/instancing/InstancedRenderDispatcher.java

@@ -29,8 +29,11 @@ public class InstancedRenderDispatcher {
 	 * @param te The tile whose instance you want to update.
 	 */
 	public static void enqueueUpdate(BlockEntity te) {
-		if (te.hasLevel() && te.getLevel() instanceof ClientLevel)
-			getTiles(te.getLevel()).queueUpdate(te);
+		if (Backend.isOn() && te.hasLevel() && te.getLevel() instanceof ClientLevel) {
+			instanceWorlds.get(te.getLevel())
+					.getTileEntityInstanceManager()
+					.queueUpdate(te);
+		}
 	}
 
 	/**
@@ -38,17 +41,29 @@ public class InstancedRenderDispatcher {
 	 * @param entity The entity whose instance you want to update.
 	 */
 	public static void enqueueUpdate(Entity entity) {
-		getEntities(entity.level).queueUpdate(entity);
+		if (Backend.isOn()) {
+			instanceWorlds.get(entity.level)
+					.getEntityInstanceManager()
+					.queueUpdate(entity);
+		}
 	}
 
 	public static InstanceManager<BlockEntity> getTiles(LevelAccessor world) {
-		return instanceWorlds.get(world)
-				.getTileEntityInstanceManager();
+		if (Backend.isOn()) {
+			return instanceWorlds.get(world)
+					.getTileEntityInstanceManager();
+		} else {
+			throw new NullPointerException("Backend is off, cannot retrieve instance world.");
+		}
 	}
 
 	public static InstanceManager<Entity> getEntities(LevelAccessor world) {
-		return instanceWorlds.get(world)
-				.getEntityInstanceManager();
+		if (Backend.isOn()) {
+			return instanceWorlds.get(world)
+					.getEntityInstanceManager();
+		} else {
+			throw new NullPointerException("Backend is off, cannot retrieve instance world.");
+		}
 	}
 
 	@SubscribeEvent
@@ -61,12 +76,15 @@ public class InstancedRenderDispatcher {
 		ClientLevel world = mc.level;
 		AnimationTickHolder.tick();
 
-		instanceWorlds.get(world).tick();
+		if (Backend.isOn()) {
+			instanceWorlds.get(world)
+					.tick();
+		}
 	}
 
 	@SubscribeEvent
 	public static void onBeginFrame(BeginFrameEvent event) {
-		if (Backend.isGameActive()) {
+		if (Backend.isGameActive() && Backend.isOn()) {
 			instanceWorlds.get(event.getWorld())
 					.beginFrame(event);
 		}

src/main/java/com/jozufozu/flywheel/event/EntityWorldHandler.java

@@ -1,5 +1,6 @@
 package com.jozufozu.flywheel.event;
 
+import com.jozufozu.flywheel.backend.Backend;
 import com.jozufozu.flywheel.backend.instancing.InstancedRenderDispatcher;
 
 import net.minecraftforge.api.distmarker.Dist;
@@ -13,13 +14,13 @@ public class EntityWorldHandler {
 
 	@SubscribeEvent
 	public static void onEntityJoinWorld(EntityJoinWorldEvent event) {
-		if (event.getWorld().isClientSide) InstancedRenderDispatcher.getEntities(event.getWorld())
+		if (event.getWorld().isClientSide && Backend.isOn()) InstancedRenderDispatcher.getEntities(event.getWorld())
 				.queueAdd(event.getEntity());
 	}
 
 	@SubscribeEvent
 	public static void onEntityLeaveWorld(EntityLeaveWorldEvent event) {
-		if (event.getWorld().isClientSide) InstancedRenderDispatcher.getEntities(event.getWorld())
+		if (event.getWorld().isClientSide && Backend.isOn()) InstancedRenderDispatcher.getEntities(event.getWorld())
 				.remove(event.getEntity());
 	}
 }

src/main/java/com/jozufozu/flywheel/mixin/ChunkRebuildHooksMixin.java

@@ -23,7 +23,7 @@ public class ChunkRebuildHooksMixin {
 	@Inject(method = "handleBlockEntity", at = @At("HEAD"), cancellable = true)
 	private <E extends BlockEntity> void addAndFilterBEs(ChunkRenderDispatcher.CompiledChunk compiledChunk, Set<BlockEntity> set, E be, CallbackInfo ci) {
 
-		if (Backend.isOn() && Backend.isFlywheelWorld(be.getLevel())) {
+		if (Backend.canUseInstancing(be.getLevel())) {
 
 			InstancedRenderRegistry registry = InstancedRenderRegistry.getInstance();
 			if (registry.canInstance(be.getType()))

src/main/java/com/jozufozu/flywheel/mixin/InstanceAddMixin.java

@@ -7,6 +7,7 @@ import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
+import com.jozufozu.flywheel.backend.Backend;
 import com.jozufozu.flywheel.backend.instancing.InstancedRenderDispatcher;
 
 import net.minecraft.world.level.Level;
@@ -26,7 +27,9 @@ public class InstanceAddMixin {
 	@Inject(method = "setBlockEntity",
 			at = @At(value = "INVOKE_ASSIGN", target = "Ljava/util/Map;put(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;"))
 	private void tileAdded(BlockEntity be, CallbackInfo ci) {
-		if (level.isClientSide) InstancedRenderDispatcher.getTiles(this.level)
-				.add(be);
+		if (level.isClientSide && Backend.isOn()) {
+			InstancedRenderDispatcher.getTiles(this.level)
+					.add(be);
+		}
 	}
 }

src/main/java/com/jozufozu/flywheel/mixin/InstanceRemoveMixin.java

@@ -8,6 +8,7 @@ import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
+import com.jozufozu.flywheel.backend.Backend;
 import com.jozufozu.flywheel.backend.instancing.InstancedRenderDispatcher;
 
 import net.minecraft.client.multiplayer.ClientLevel;
@@ -23,8 +24,10 @@ public class InstanceRemoveMixin {
 
 	@Inject(at = @At("TAIL"), method = "setRemoved")
 	private void removeInstance(CallbackInfo ci) {
-		if (level instanceof ClientLevel) InstancedRenderDispatcher.getTiles(this.level)
-				.remove((BlockEntity) (Object) this);
+		if (level instanceof ClientLevel && Backend.isOn()) {
+			InstancedRenderDispatcher.getTiles(this.level)
+					.remove((BlockEntity) (Object) this);
+		}
 	}
 
 //	/**

src/main/java/com/jozufozu/flywheel/mixin/RenderHooksMixin.java

@@ -86,7 +86,9 @@ public class RenderHooksMixin {
 	 */
 	@Inject(at = @At("TAIL"), method = "setBlockDirty(Lnet/minecraft/core/BlockPos;Lnet/minecraft/world/level/block/state/BlockState;Lnet/minecraft/world/level/block/state/BlockState;)V")
 	private void checkUpdate(BlockPos pos, BlockState lastState, BlockState newState, CallbackInfo ci) {
-		InstancedRenderDispatcher.getTiles(level)
-				.update(level.getBlockEntity(pos));
+		if (Backend.isOn()) {
+			InstancedRenderDispatcher.getTiles(level)
+					.update(level.getBlockEntity(pos));
+		}
 	}
 }