Complain if IMC adds a handler/catalyst for a handlerID that doesn't exist.

src/main/java/codechicken/nei/recipe/GuiRecipeTab.java

@@ -11,6 +11,8 @@ import java.nio.channels.Channels;
 import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 import java.util.*;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import net.minecraft.client.gui.FontRenderer;
 import net.minecraft.item.ItemStack;
@@ -282,6 +284,24 @@ public abstract class GuiRecipeTab extends Widget {
         handlerMap.keySet().removeAll(handlerRemoverFromIMC);
         handlerMap.putAll(handlerAdderFromIMC);
 
+        if (!handlerAdderFromIMC.isEmpty()) {
+            // If we're getting an IMC message, it probably means it should match
+            Set<String> handlerIds = Stream
+                    .concat(
+                            GuiCraftingRecipe.serialCraftingHandlers.stream(),
+                            GuiCraftingRecipe.craftinghandlers.stream())
+                    .map(ICraftingHandler::getHandlerId).collect(Collectors.toSet());
+            handlerAdderFromIMC.keySet().stream().forEach(handlerName -> {
+                if (!handlerIds.contains(handlerName)) {
+                    NEIClientConfig.logger.warn("Could not find a registered handlerID that matches " + handlerName);
+                    handlerIds.forEach(handler -> {
+                        if (handler.equalsIgnoreCase(handlerName)) {
+                            NEIClientConfig.logger.warn("  -- Did you mean: " + handler);
+                        }
+                    });
+                }
+            });
+        }
         NEIClientConfig.logger.info("Sending {}", NEIRegisterHandlerInfosEvent.class.getSimpleName());
         MinecraftForge.EVENT_BUS.post(new NEIRegisterHandlerInfosEvent());
     }

src/main/java/codechicken/nei/recipe/RecipeCatalysts.java

@@ -15,6 +15,9 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import net.minecraft.item.ItemStack;
 
@@ -227,6 +230,24 @@ public class RecipeCatalysts {
             }
         }
 
+        if (!catalystsAdderFromIMC.isEmpty()) {
+            // If we're getting an IMC message, it probably means it should match
+            Set<String> handlerIds = Stream
+                    .concat(
+                            GuiCraftingRecipe.serialCraftingHandlers.stream(),
+                            GuiCraftingRecipe.craftinghandlers.stream())
+                    .map(ICraftingHandler::getHandlerId).collect(Collectors.toSet());
+            catalystsAdderFromIMC.keySet().stream().forEach(handlerName -> {
+                if (!handlerIds.contains(handlerName)) {
+                    NEIClientConfig.logger.warn("Could not find a registered handlerID that matches " + handlerName);
+                    handlerIds.forEach(handler -> {
+                        if (handler.equalsIgnoreCase(handlerName)) {
+                            NEIClientConfig.logger.warn("  -- Did you mean: " + handler);
+                        }
+                    });
+                }
+            });
+        }
         for (Map.Entry<String, List<ItemStack>> entry : catalystsRemoverFromAPI.entrySet()) {
             String handlerID = entry.getKey();
             if (recipeCatalystMap.containsKey(handlerID)) {