code: function validateProviderUri (provider, webId) {
    if (!provider) {
      let error = new Error(`OIDC issuer not advertised for ${webId}.
      See https://github.com/solid/webid-oidc-spec#authorized-oidc-issuer-discovery`)
      error.statusCode = 400
      throw error
    }
  
    if (!validUrl.isUri(provider)) {
      let error = new Error(`OIDC issuer for ${webId} is not a valid URI: ${provider}`)
      error.statusCode = 400
      throw error
    }
  }
docs: Validates a preferred provider uri (makes sure it's a well-formed URI).
  
  @param provider {string} Identity provider URI
  
  @throws {Error} If the URI is invalid