feat(langgraph): update troubleshooting deep link to new docs, add MISSING_CHECKPOINTER reference error (#1617)

Author: dqbd

.changeset/late-islands-work.md

@@ -0,0 +1,5 @@
+---
+"@langchain/langgraph": patch
+---
+
+Update troubleshooting link for common errors, add MISSING_CHECKPOINTER troubleshooting page

libs/langgraph/src/errors.ts

@@ -7,6 +7,7 @@ export type BaseLangGraphErrorFields = {
     | "GRAPH_RECURSION_LIMIT"
     | "INVALID_CONCURRENT_GRAPH_UPDATE"
     | "INVALID_GRAPH_NODE_RETURN_VALUE"
+    | "MISSING_CHECKPOINTER"
     | "MULTIPLE_SUBGRAPHS"
     | "UNREACHABLE_NODE";
 };
@@ -19,7 +20,7 @@ export class BaseLangGraphError extends Error {
   constructor(message?: string, fields?: BaseLangGraphErrorFields) {
     let finalMessage = message ?? "";
     if (fields?.lc_error_code) {
-      finalMessage = `${finalMessage}\n\nTroubleshooting URL: https://langchain-ai.github.io/langgraphjs/troubleshooting/errors/${fields.lc_error_code}/\n`;
+      finalMessage = `${finalMessage}\n\nTroubleshooting URL: https://docs.langchain.com/oss/javascript/langgraph/${fields.lc_error_code}/\n`;
     }
     super(finalMessage);
     this.lc_error_code = fields?.lc_error_code;

libs/langgraph/src/interrupt.ts

@@ -73,7 +73,11 @@ export function interrupt<I = unknown, R = any>(value: I): R {
   }
 
   const checkpointer: BaseCheckpointSaver = conf[CONFIG_KEY_CHECKPOINTER];
-  if (!checkpointer) throw new GraphValueError("No checkpointer set");
+  if (!checkpointer) {
+    throw new GraphValueError("No checkpointer set", {
+      lc_error_code: "MISSING_CHECKPOINTER",
+    });
+  }
 
   // Track interrupt index
   const scratchpad: PregelScratchpad = conf[CONFIG_KEY_SCRATCHPAD];

libs/langgraph/src/pregel/index.ts

@@ -931,7 +931,9 @@ export class Pregel<
     const checkpointer =
       config.configurable?.[CONFIG_KEY_CHECKPOINTER] ?? this.checkpointer;
     if (!checkpointer) {
-      throw new GraphValueError("No checkpointer set");
+      throw new GraphValueError("No checkpointer set", {
+        lc_error_code: "MISSING_CHECKPOINTER",
+      });
     }
 
     const checkpointNamespace: string =
@@ -991,7 +993,9 @@ export class Pregel<
     const checkpointer: BaseCheckpointSaver =
       config.configurable?.[CONFIG_KEY_CHECKPOINTER] ?? this.checkpointer;
     if (!checkpointer) {
-      throw new GraphValueError("No checkpointer set");
+      throw new GraphValueError("No checkpointer set", {
+        lc_error_code: "MISSING_CHECKPOINTER",
+      });
     }
 
     const checkpointNamespace: string =
@@ -1065,7 +1069,9 @@ export class Pregel<
     const checkpointer: BaseCheckpointSaver | undefined =
       startConfig.configurable?.[CONFIG_KEY_CHECKPOINTER] ?? this.checkpointer;
     if (!checkpointer) {
-      throw new GraphValueError("No checkpointer set");
+      throw new GraphValueError("No checkpointer set", {
+        lc_error_code: "MISSING_CHECKPOINTER",
+      });
     }
     if (supersteps.length === 0) {
       throw new Error("No supersteps provided");
@@ -2038,12 +2044,7 @@ export class Pregel<
       stream.push([ns ?? [], "custom", chunk]);
     };
 
-    config.interrupt ??=
-      this.checkpointer != null
-        ? interrupt
-        : () => {
-            throw new GraphValueError("No checkpointer set");
-          };
+    config.interrupt ??= interrupt;
 
     const callbackManager = await getCallbackManagerForConfig(config);
     const runManager = await callbackManager?.handleChainStart(