add fabric mod information to crash reports

src/main/java/net/fabricmc/fabric/FabricAPI.java

@@ -28,9 +28,16 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Facing;
 import net.minecraft.world.World;
 
+import java.util.List;
+
 public class FabricAPI implements ModInitializer {
 	@Override
 	public void onInitialize() {
+		List<String> ss = null;
+		for (String s : ss) {
+			s.length();
+		}
+
 		PlayerInteractionEvent.BREAK_BLOCK.register((player, world, hand, pos, facing) -> {
 			BlockState state = world.getBlockState(pos);
 			if (state instanceof BreakInteractable) {

src/main/java/net/fabricmc/fabric/mixin/misc/MixinCrashReport.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.misc;
+
+import com.google.common.collect.Lists;
+import net.fabricmc.loader.FabricLoader;
+import net.fabricmc.loader.ModContainer;
+import net.fabricmc.loader.ModInfo;
+import net.minecraft.util.SystemUtil;
+import net.minecraft.util.crash.CrashReport;
+import net.minecraft.util.crash.CrashReportElement;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+import java.util.*;
+
+@Mixin(CrashReport.class)
+public abstract class MixinCrashReport {
+	@Shadow
+	public abstract CrashReportElement getElement();
+
+	@Inject(at = @At("HEAD"), method = "generateWittyComment", cancellable = true)
+	private static void generateWittyComment(CallbackInfoReturnable<String> info) {
+		if (SystemUtil.getMeasuringTimeNano() % 14723 == 0) {
+			info.setReturnValue("OOPSIE WOOPSIE!! Uwu We made a fucky wucky!! A wittle fucko boingo! The code monkeys at our headquarters are working VEWY HAWD to fix this!");
+			info.cancel();
+		}
+	}
+
+	@Inject(at = @At("RETURN"), method = "method_559")
+	private void method_559(CallbackInfo info) {
+		getElement().add("Fabric Mods", () -> {
+			Map<String, String> mods = new TreeMap<>();
+			for (ModContainer container : FabricLoader.INSTANCE.getMods()) {
+				mods.put(container.getInfo().getName(), container.getInfo().getVersionString() + " (" + container.getOriginFile().getName() + ")");
+			}
+
+			StringBuilder modString = new StringBuilder();
+
+			for (String id : mods.keySet()) {
+				modString.append("\n\t\t");
+				modString.append(id);
+				modString.append(": ");
+				modString.append(mods.get(id));
+			}
+
+			return modString.toString();
+		});
+	}
+}

src/main/resources/net.fabricmc.fabric.mixins.common.json

@@ -16,6 +16,7 @@
     "events.server.MixinMinecraftServer",
     "events.tick.MixinMinecraftServer",
     "events.tick.MixinWorld",
+    "misc.MixinCrashReport",
     "networking.MixinServerPlayNetworkHandler",
     "networking.MixinSPacketCustomPayload",
     "registry.MixinBootstrap",