Function assertDescriptor

src/keyboard/getNextKeyDef.ts:175–183

(
  descriptor: string | undefined,
  text: string,
  pos: number,
)

}

function assertDescriptor(
  descriptor: string | undefined,
  text: string,
  pos: number,
): asserts descriptor is string {
  if (!descriptor) {
    throw new Error(getErrorMessage('key descriptor', text[pos], text))
  }
}

function getEnumValue<T>(f: Record<string, T>, key: string): T | undefined {
  return f[key]