```ts
/** The KEY=VALUE pairs of a config file. */
export function parseConfig(text: string): Record<string, string> {
  const config: Record<string, string> = {};
  for (const line of text.split("\n")) {
    const trimmedLine = line.trim();
    if (!trimmedLine || trimmedLine.startsWith("#")) continue;
    const [key, value] = trimmedLine.split("=", 2).map((part) => part.trim());
    if (!key || key === "__proto__") throw new Error(`Invalid key on line: ${line}`);
    config[key] = value || "";
  }
  return config;
}
```