denoland/deno · error · Error

Cannot get cursor before first iteration

Error message

Cannot get cursor before first iteration

What it means

Error "Cannot get cursor before first iteration" thrown in denoland/deno.

Source

Thrown at ext/kv/01_db.ts:904

        this.#selector = { start, end };
      } else {
        throw new TypeError(
          "Selector must specify either 'prefix' or both 'start' and 'end' key",
        );
      }
    }
    ObjectFreeze(this.#selector);
    this.#pullBatch = pullBatch;
    this.#limit = limit;
    this.#reverse = reverse;
    this.#consistency = consistency;
    this.#batchSize = batchSize;
    this.#cursorGen = cursor ? () => cursor : null;
  }

  get cursor(): string {
    if (this.#cursorGen === null) {
      throw new Error("Cannot get cursor before first iteration");
    }

    return this.#cursorGen();
  }

  async next(): Promise<IteratorResult<Deno.KvEntry<unknown>>> {
    // Fused or limit exceeded
    if (
      this.#done ||
      (this.#limit !== undefined && this.#count >= this.#limit)
    ) {
      return { done: true, value: undefined };
    }

    // Attempt to fill the buffer
    if (!this.#entries?.length && !this.#lastBatch) {
      const batch = await this.#pullBatch(
        this.#selector,

View on GitHub (pinned to 89f33cbef2)

When it happens

Trigger: Thrown at ext/kv/01_db.ts:904 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/95f7a2fc2b9d5fe6. Report an issue: GitHub.