```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);
    if (!key) throw new Error(`Empty key on line: ${line}`);
    
    if (config[key]) delete config[key];
    
    key = key.trim();
    value = value ? value.trim() : "";
    
    config[key] = value;
  }
  return config;
}
```