diff --git a/src/main/java/org/ladysnake/blabber/api/DialogueIllustrationType.java b/src/main/java/org/ladysnake/blabber/api/DialogueIllustrationType.java
index 83389458..fe4fa5da 100644
--- a/src/main/java/org/ladysnake/blabber/api/DialogueIllustrationType.java
+++ b/src/main/java/org/ladysnake/blabber/api/DialogueIllustrationType.java
@@ -19,6 +19,7 @@
 
 import com.mojang.serialization.Codec;
 import net.minecraft.network.PacketByteBuf;
+import org.jetbrains.annotations.ApiStatus;
 import org.ladysnake.blabber.impl.common.BlabberRegistrar;
 
 import java.util.function.BiConsumer;
@@ -71,6 +72,7 @@ public void writeToPacket(PacketByteBuf buf, T toWrite) {
      * Same as writeToPacket, but does an unchecked cast, for when the type information is lost somewhere.
      * Make sure it's safe.
      */
+    @ApiStatus.Internal
     public void writeToPacketUnsafe(PacketByteBuf buf, DialogueIllustration illustration) {
         //noinspection unchecked
         this.writeToPacket(buf, (T) illustration);
diff --git a/src/main/java/org/ladysnake/blabber/impl/common/validation/DialogueValidator.java b/src/main/java/org/ladysnake/blabber/impl/common/validation/DialogueValidator.java
index df2cc1fe..d776df18 100644
--- a/src/main/java/org/ladysnake/blabber/impl/common/validation/DialogueValidator.java
+++ b/src/main/java/org/ladysnake/blabber/impl/common/validation/DialogueValidator.java
@@ -93,7 +93,7 @@ public static ValidationResult validateStructure(DialogueTemplate dialogue) {
         for (Map.Entry<String, DialogueState> state : dialogue.states().entrySet()) {
             for (String illustration : state.getValue().illustrations()) {
                 if (!dialogue.illustrations().containsKey(illustration)) {
-                    warnings.add(new ValidationResult.Warning.NonexistentIllustrationList(state.getKey(), illustration));
+                    return new ValidationResult.Error.NonexistentIllustrationList(state.getKey(), illustration);
                 }
             }
         }
diff --git a/src/main/java/org/ladysnake/blabber/impl/common/validation/ValidationResult.java b/src/main/java/org/ladysnake/blabber/impl/common/validation/ValidationResult.java
index dd4ffc02..eff11917 100644
--- a/src/main/java/org/ladysnake/blabber/impl/common/validation/ValidationResult.java
+++ b/src/main/java/org/ladysnake/blabber/impl/common/validation/ValidationResult.java
@@ -53,14 +53,6 @@ public String message() {
                 return state() + " only has conditional paths to the end of the dialogue";
             }
         }
-
-        record NonexistentIllustrationList(String state, String illustration) implements Warning {
-
-            @Override
-            public String message() {
-                return state() + " references non-existent illustration list " + illustration();
-            }
-        }
     }
 
     sealed interface Error extends ValidationResult {
@@ -81,5 +73,12 @@ public String message() {
                 return state() + " does not have any path to the end of the dialogue";
             }
         }
+
+        record NonexistentIllustrationList(String state, String illustration) implements Error {
+            @Override
+            public String message() {
+                return state() + " references non-existent illustration list " + illustration();
+            }
+        }
     }
 }