As will become obvious, I am new to Eagle and PCB layout. I set out a simple design, starting with a power jack. The power jack seems to clearly have a "+" terminal labelled, so I connected that to the positive input of my 5V step-down converter.
On the board layout, I should have noticed that what I thought was the positive terminal was labelled GND (but alas, I did not notice):
However, the board passed ERC.
Did I misinterpret the "+" symbol on the schematic view? I would appreciate any insight into my error.