Catch redirect errors when forked

src/main/java/com/mojang/brigadier/CommandDispatcher.java

@@ -111,6 +111,7 @@ public class CommandDispatcher<S> {
                             }
                             next.add(child.copyFor(context.getSource()));
                         } else {
+                            try {
                                 final Collection<S> results = modifier.apply(context);
                                 if (!results.isEmpty()) {
                                     if (next == null) {
@@ -120,6 +121,12 @@ public class CommandDispatcher<S> {
                                         next.add(child.copyFor(source));
                                     }
                                 }
+                            } catch (final CommandSyntaxException ex) {
+                                consumer.onCommandComplete(context, false, 0);
+                                if (!forked) {
+                                    throw ex;
+                                }
+                            }
                         }
                     }
                 } else if (context.getCommand() != null) {

src/main/java/com/mojang/brigadier/SingleRedirectModifier.java

@@ -0,0 +1,11 @@
+package com.mojang.brigadier;
+
+import com.mojang.brigadier.context.CommandContext;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
+
+import java.util.Collection;
+
+@FunctionalInterface
+public interface SingleRedirectModifier<S> {
+    S apply(CommandContext<S> context) throws CommandSyntaxException;
+}

src/main/java/com/mojang/brigadier/builder/ArgumentBuilder.java

@@ -2,13 +2,12 @@ package com.mojang.brigadier.builder;
 
 import com.mojang.brigadier.Command;
 import com.mojang.brigadier.RedirectModifier;
-import com.mojang.brigadier.context.CommandContext;
+import com.mojang.brigadier.SingleRedirectModifier;
 import com.mojang.brigadier.tree.CommandNode;
 import com.mojang.brigadier.tree.RootCommandNode;
 
 import java.util.Collection;
 import java.util.Collections;
-import java.util.function.Function;
 import java.util.function.Predicate;
 
 public abstract class ArgumentBuilder<S, T extends ArgumentBuilder<S, T>> {
@@ -63,7 +62,7 @@ public abstract class ArgumentBuilder<S, T extends ArgumentBuilder<S, T>> {
         return forward(target, null, false);
     }
 
-    public T redirect(final CommandNode<S> target, final Function<CommandContext<S>, S> modifier) {
+    public T redirect(final CommandNode<S> target, final SingleRedirectModifier<S> modifier) {
         return forward(target, modifier == null ? null : o -> Collections.singleton(modifier.apply(o)), false);
     }