Fix NPE in RamseteCommand (#2019)

wpilibj/src/main/java/edu/wpi/first/wpilibj2/command/RamseteCommand.java

@@ -35,10 +35,12 @@ import static edu.wpi.first.wpilibj.util.ErrorMessages.requireNonNullParam;
  * the PID and feedforward functionality, returning only the raw wheel speeds from the RAMSETE
  * controller.
  */
+@SuppressWarnings("PMD.TooManyFields")
 public class RamseteCommand extends CommandBase {
   private final Timer m_timer = new Timer();
   private DifferentialDriveWheelSpeeds m_prevSpeeds;
   private double m_prevTime;
+  private final boolean m_usePID;
 
   private final Trajectory m_trajectory;
   private final Supplier<Pose2d> m_pose;
@@ -113,6 +115,8 @@ public class RamseteCommand extends CommandBase {
     m_rightController = requireNonNullParam(rightController, "rightController", "RamseteCommand");
     m_output = requireNonNullParam(outputVolts, "outputVolts", "RamseteCommand");
 
+    m_usePID = true;
+
     addRequirements(requirements);
   }
 
@@ -150,6 +154,8 @@ public class RamseteCommand extends CommandBase {
     m_leftController = null;
     m_rightController = null;
 
+    m_usePID = false;
+
     addRequirements(requirements);
   }
 
@@ -164,8 +170,10 @@ public class RamseteCommand extends CommandBase {
                               * initialState.velocityMetersPerSecond));
     m_timer.reset();
     m_timer.start();
-    m_leftController.reset();
-    m_rightController.reset();
+    if (m_usePID) {
+      m_leftController.reset();
+      m_rightController.reset();
+    }
   }
 
   @Override
@@ -182,7 +190,7 @@ public class RamseteCommand extends CommandBase {
     double leftOutput;
     double rightOutput;
 
-    if (m_leftController != null) {
+    if (m_usePID) {
       double leftFeedforward =
           m_ks * Math.signum(leftSpeedSetpoint)
               + m_kv * leftSpeedSetpoint