Function folderStyleNameProblem

src/core/id.ts:24–41

(
  value: string,
  label: string
)

 * description, or null when valid.
 */
export function folderStyleNameProblem(
  value: string,
  label: string
): string | null {
  if (value.length === 0) {
    return `${label} must not be empty`;
  }

  if (value === '.' || value === '..') {
    return `${label} must not be '${value}'`;
  }

  if (/[\\/]/u.test(value)) {
    return `${label} must not contain path separators`;
  }

  return null;
}