fix: clean up bridge error conversion and add debug logging

Remove redundant UnknownError case that duplicated the default branch,
add debug logging for unrecognized bridge error types to aid
troubleshooting, and document the ServiceError cast behavior.

Author: w1am

packages/db-client/src/utils/convertBridgeError.ts

@@ -7,10 +7,15 @@ import {
   DeadlineExceededError,
   UnknownError,
 } from "./CommandError";
+import { debug } from "./debug";
 import { ServiceError } from "@grpc/grpc-js";
 
 export const convertBridgeError = (error: Error, streamName?: string) => {
   const stream = streamName ?? "unknown stream";
+
+  // Bridge errors are plain Error objects from the Rust native addon with
+  // name, message, and metadata (plain object). They lack gRPC-specific
+  // ServiceError properties (code, details) but CommandErrorBase handles this.
   const serviceError = error as ServiceError;
 
   switch (error.name) {
@@ -26,9 +31,12 @@ export const convertBridgeError = (error: Error, streamName?: string) => {
       return new UnavailableError(serviceError);
     case "DeadlineExceededError":
       return new DeadlineExceededError(serviceError);
-    case "UnknownError":
-      return new UnknownError(serviceError);
     default:
+      debug.connection(
+        "Unrecognized bridge error type '%s': %s",
+        error.name,
+        error.message
+      );
       return new UnknownError(serviceError);
   }
 };