COLUMBUS — Ohio Gov. Mike DeWine has signed into law a bill fixing what gun rights advocates said was a mistake that could have inadvertently banned several types of legal guns. At issue was legislation approved by lawmakers last year that allows off-duty police officers to carry firearms and limits local governments’ ability to pass gun laws, among other changes. Gun advocates said a misplaced paragraph in the bill unintentionally lumped a variety of long guns into a prohibited category. They asked lawmakers to fix the problem before the original law took effect in late March. The Republican governor signed the bill Monday after lawmakers approved the legislation earlier this month. It takes effect immediately.