```ts
export function parseSemver(version: string): { major: number; minor: number; patch: number; prerelease: string | null; build: string | null } {
  /** Check that version is a valid SemVer string */
  if (!/^\d+\.\d+\.\d+(?:-\S+)?(?:\+\S+)?$/.test(version)) {
    throw new Error(`Invalid SemVer version format '${version}'`);
  }

  const match = version.match(/^(\d+)\.(\d+)\.(\d+)?(?:-(.+))?(:(.+))?$/);
  if (!match) {
    throw new Error(`Invalid SemVer version format '${version}'`);
  }

  return {
    major: parseInt(match[1], 10),
    minor: parseInt(match[2], 10),
    patch: parseInt(match[3], 10),
    prerelease: match[4] || null,
    build: match[5] || null
  };
}
```