Bad termination after program completes

Question

I wrote a MPI program in C to test sending/receiving messages between nodes.

#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>

int main(int* argc, char*** argv){
  MPI_Init(NULL, NULL);

  int rank;
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  int size;
  MPI_Comm_size(MPI_COMM_WORLD, &size);

  if(size < 2){
    fprintf(stderr, "Must have >2 processes.\n");
    MPI_Abort(MPI_COMM_WORLD, 1);
  }

  int number;
  if(rank == 0){
    number = -1;
    MPI_Send(&number, 1, MPI_INT, 1, 0, MPI_COMM_WORLD);
  }

  else if(rank == 1){
    MPI_Recv(&number, 1, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
    printf("Received number %d from process 0.\n", number);
  }
  MPI_Finalize();
}

When running on 2 machines with one process each, the program provides the correct output:

Received number -1 from process 0.

But also throws the error:

================================================================================
=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
=   PID 4529 RUNNING AT node0
=   EXIT CODE: 2
=   CLEANING UP REMAINING PROCESSES
=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
===================================================================================

Most resources I've found on bad terminations are dealing with segfaults rather than exit code 2. I've tried adding an MPI_Barrier right before MPI_Finalize, which adds an "assert (!closed) failed" error.

Both nodes are using MPICH 3.1.4 on Raspbian 2015-05-05.