fix null io

Signed-off-by: Dasun Abeykoon <[email protected]>

Author: dabeycorn

src/main/java/org/frc6423/robot/subsystems/arm/ArmIONone.java

@@ -26,6 +26,11 @@ public double getPivotStatorCurrentAmps() {
     return 0.0;
   }
 
+  @Override
+  public double getRollerSpeedRpm() {
+    return 0.0;
+  }
+
   @Override
   public double getRollerStatorCurrentAmps() {
     return 0.0;