Surface ldapjs's real parser/error cause instead of a generic "closed"

Neither raising the client timeout nor switching to paged search fixed
the directory-wide import browse — narrowing it down with a plain
ldapsearch (same filter, run from inside this exact container, both
dn-only and full-attribute) showed the network path and response
content are both fine; a standard LDAP client handles it without issue.
That leaves ldapjs's own response handling. Its client-level `error`
event (e.g. a BER/protocol parser failure) forcibly closes the socket,
but we were swallowing that event silently — so every failure surfaced
as the same uninformative "<id> closed" ConnectionError regardless of
what actually went wrong. Now the last captured client `error` is
attached to the bind/search rejection instead, so the UI's error
message will show the real underlying cause next time this fails.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012o9j9RezxbZVKQMrB7oRLY

src/lib/ldap/client.ts

@@ -13,6 +13,13 @@ interface ConnectionSettings {
   useTls: boolean;
 }
 
+// ldapjs's client-level `error` event fires for things like a BER/protocol
+// parser failure on the response stream — which then also forcibly closes
+// the socket, so the pending bind/search callback only ever sees a generic
+// "<id> closed" ConnectionError with no hint of the real cause. Stashing the
+// last `error` payload per client lets callers report the actual reason.
+const lastClientError = new WeakMap<ldap.Client, Error>();
+
 function createLdapClient(settings: ConnectionSettings, timeoutMs = 5_000): ldap.Client {
   const protocol = settings.useTls ? "ldaps" : "ldap";
   const client = ldap.createClient({
@@ -26,15 +33,24 @@ function createLdapClient(settings: ConnectionSettings, timeoutMs = 5_000): ldap
     connectTimeout: 5_000,
   });
   // A socket-level error (e.g. host unreachable) with no listener would
-  // throw and crash the process — swallow it here, every call site already
-  // handles failure via the bind/search callback's error argument.
-  client.on("error", () => {});
+  // throw and crash the process — every call site already handles failure
+  // via the bind/search callback's error argument, so this only needs to
+  // record the error for that fallback, never rethrow.
+  client.on("error", (err) => {
+    lastClientError.set(client, err);
+  });
   return client;
 }
 
+/** Prefers the client's last captured `error` event over a generic connection-closed error, since the former usually carries the real cause. */
+function describeError(client: ldap.Client, err: Error): Error {
+  const captured = lastClientError.get(client);
+  return captured ?? err;
+}
+
 function bind(client: ldap.Client, dn: string, password: string): Promise<void> {
   return new Promise((resolve, reject) => {
-    client.bind(dn, password, (err) => (err ? reject(err) : resolve()));
+    client.bind(dn, password, (err) => (err ? reject(describeError(client, err)) : resolve()));
   });
 }
 
@@ -55,7 +71,7 @@ function search(
     // stream of `searchEntry` events followed by a single `end`.
     client.search(baseDn, { filter, scope: "sub", paged: { pageSize: 200 } }, (err, res) => {
       if (err) {
-        reject(err);
+        reject(describeError(client, err));
         return;
       }
       res.on("searchEntry", (entry) => {
@@ -65,7 +81,7 @@ function search(
         }
         results.push({ dn: entry.objectName ?? entry.pojo.objectName, attributes });
       });
-      res.on("error", (searchErr) => reject(searchErr));
+      res.on("error", (searchErr) => reject(describeError(client, searchErr)));
       res.on("end", () => resolve(results));
     });
   });