deepseek-ai/deepseek-harness · error · TypeError

skill provider "${providerName}" list() must return an array

Error message

skill provider "${providerName}" list() must return an array or { candidates, complete } observation

What it means

Error "skill provider "${providerName}" list() must return an array or { candidates, complete } observation" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/skill/skill/src/index.ts:668

    for (const callback of this.ctx.events.dispatch('emit', ['skills/change'])) {
      try {
        const returned: unknown = callback()
        void Promise.resolve(returned).catch((error: unknown) => {
          this.ctx.logger.warn(`skills/change listener rejected: ${errorMessage(error)}`)
        })
      } catch (error: unknown) {
        this.ctx.logger.warn(`skills/change listener threw: ${errorMessage(error)}`)
      }
    }
  }
}

function normalizeProviderObservation(output: unknown, providerName: string): SkillProviderObservation {
  if (Array.isArray(output)) {
    return { candidates: output as readonly SkillCandidate[], complete: true }
  }
  if (output === null || typeof output !== 'object') {
    throw invalidProviderObservation(providerName)
  }
  const observation = output as Partial<SkillProviderObservation>
  if (!Array.isArray(observation.candidates) || typeof observation.complete !== 'boolean') {
    throw invalidProviderObservation(providerName)
  }
  return observation as SkillProviderObservation
}

function invalidProviderObservation(providerName: string): TypeError {
  return new TypeError(`skill provider "${providerName}" list() must return an array or { candidates, complete } observation`)
}

const RUNTIME_SKILL_PROVIDER: SkillProvider = {
  name: RUNTIME_PROVIDER,
  /* v8 ignore next -- Runtime skills are injected directly by the registry; this provider only owns `get()`. */
  list() {
    return Promise.resolve([])
  },

View on GitHub (pinned to b150a551b8)

Solutions

1. Fix the provider list() to return an array or a { candidates, complete } observation.

When it happens

Trigger: Thrown at packages/skill/skill/src/index.ts:668 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/b3abf70e401249fe. Report an issue: GitHub.