Your limits of integration is from 0 to 2.5 seconds. But within those limits you have two distinct segments. First segment is where v(t)=10 volts, this segment is from 0 to 2 seconds. Second segment is where v(t)=0 volts, this segment is from 2 to 2.5 seconds.
Since integral of zero is zero, you really only have the integral from 0 to 2 seconds plus 1 A.
And, of course, you integral at 4 seconds is also wrong.