Welche Bedeutung steckt hinter der hier vorgestellten Vokabel aus dem Bereich In the news?

In the news: A sign welcoming visitors to Chadderton, a town in the Greater Manchester area, had been erected upside down. Luckily, residents soon noticed the blunder and contacted the local town hall about it.

a blunder

Do you know what it means?

• an error
• a joke
• an insult