错误：方法声明无效;需要返回类型（第31行）

I know it's a bit of code but it's really driving me crazy:( It keeps throwing the error that method dfs() is expecting a return type on line 31, HOWEVER it is declared to return a void! What is going on here? I seem to have checked all the brackets and the scope looks good idk what is causing this! Thank you for the help! I know it's a bit of code but it's really drivi