FRANKFURT — The head of Germany's central bank has called for the EU to issue more joint debt, putting him at odds with Chancellor Friedrich Merz who wants to keep it strictly as a response to emergencies. “To make Europe attractive also means to attract investors from outside,” the German central bank governor, Joachim Nagel, told POLITICO ahead of an informal summit of EU leaders on Thursday to address the bloc’s economic challenges. “A more liquid European market when it comes to safe