```ts
export function parseSemver(version: string): { major: number; minor: number; patch: number; prerelease: string | null; build: string | null } {
  const regex = /^(\d+)\.(\d+)\.(\d+)(?:-(\w+))?(?:\+(\w+))?$/;
  const match = version.match(regex);

  if (!match) {
    throw new Error(`Invalid semver format: ${version}`);
  }

  const [_, major, minor, patch, prerelease, build] = match;

  return {
    major: parseInt(major, 10),
    minor: parseInt(minor, 10),
    patch: parseInt(patch, 10),
    prerelease: prerelease || null,
    build: build || null,
  };
}
```