ianstormtaylor/slate · error · Error

Got non-numeric path index

Error message

Got non-numeric path index

What it means

Node.getIf() iterates over path segments and requires each segment to be a number. A segment was something else (string, undefined, null), which means the path is malformed rather than merely pointing at a missing node. Unlike Node.get, this error cannot be avoided by the usual existence check — it signals a type bug in the caller's path construction.

Source

Thrown at packages/slate/src/interfaces/node.ts:438

    const node = Node.getIf(root, path)
    if (node === undefined) {
      throw new Error(
        `Cannot find a descendant at path [${path}] in node: ${Scrubber.stringify(
          root
        )}`
      )
    }
    return node
  },

  getIf(root: Node, path: Path): Node | undefined {
    let node = root

    for (let i = 0; i < path.length; i++) {
      const p = path[i]

      if (typeof p !== 'number') {
        throw new Error('Got non-numeric path index')
      }

      if (Node.isText(node) || !node.children[p]) {
        return
      }

      node = node.children[p]
    }

    return node
  },

  has(root: Node, path: Path): boolean {
    let node = root

    for (let i = 0; i < path.length; i++) {
      const p = path[i]

View on GitHub (pinned to 72a37c701e)

Solutions

1. Validate/normalize the path to numbers before use: path.every(p => typeof p === 'number') or map with Number().
2. Type paths explicitly as Path (number[]) instead of any/string[] so the compiler catches bad construction.
3. When ingesting external paths, sanitize: const p = raw.map(Number).filter(n => Number.isInteger(n)).
4. Fix the source of the path: usually string concatenation ('' + index) or optional chaining producing undefined.

Example fix

// before
const path = [String(index), 0] // oops: string segment
const node = Node.getIf(editor, path)

// after
const path = [index, 0]
const node = Node.getIf(editor, path as Path)

if (!path.every(p => Number.isInteger(p))) { /* reject/normalize path */ }

const isPath = (p: unknown): p is Path => Array.isArray(p) && p.every(n => Number.isInteger(n))

When it happens

Trigger: Passing a path built by spreading a string or mixed array like ['0', 1]; a path containing undefined due to array holes ([ , 0]); JSON-parsed paths where a segment became a string; concatenating a path with a non-numeric value.

Common situations: Serializing/deserializing paths as strings and forgetting to convert back to numbers; building paths from untyped external data (URL params, localStorage, server payloads) without validation; TypeScript any-typed path plumbing erasing safety.

Related errors

• Got non-numeric path index
• Cannot get the relative path of [${path}] inside ancestor [$
• Unable to find the path for Slate node: ${Scrubber.stringify
• Cannot get the next node from the root node!
• Cannot get the previous node from the root node!

AI-assisted analysis of ianstormtaylor/slate@72a37c701e (2026-08-27). Data as JSON: /api/errors/40c2ccf16b61d04c. Report an issue: GitHub.