fix return value of run not captured

src/main/java/carpet/mixins/CommandSourceStack_scarpetMixin.java

@@ -0,0 +1,29 @@
+package carpet.mixins;
+
+import carpet.fakes.CommandSourceStackInterface;
+import net.minecraft.commands.CommandResultCallback;
+import net.minecraft.commands.CommandSigningContext;
+import net.minecraft.commands.CommandSourceStack;
+import net.minecraft.commands.arguments.EntityAnchorArgument;
+import net.minecraft.util.TaskChainer;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Mutable;
+import org.spongepowered.asm.mixin.Shadow;
+
+@Mixin(CommandSourceStack.class)
+public class CommandSourceStack_scarpetMixin implements CommandSourceStackInterface {
+    @Mutable @Shadow private boolean silent;
+    @Mutable @Shadow private CommandResultCallback resultCallback;
+    @Mutable @Shadow private EntityAnchorArgument.Anchor anchor;
+    @Mutable @Shadow private CommandSigningContext signingContext;
+    @Mutable @Shadow private TaskChainer chatMessageChainer;
+
+    @Override
+    public void setupPrivates(boolean bl, CommandResultCallback commandResultCallback, EntityAnchorArgument.Anchor anchor, CommandSigningContext commandSigningContext, TaskChainer taskChainer) {
+        this.silent = bl;
+        this.resultCallback = commandResultCallback;
+        this.anchor = anchor;
+        this.signingContext = commandSigningContext;
+        this.chatMessageChainer = taskChainer;
+    }
+}