Operation on ... may be undefined?

I have the following code

FRAME frameArray[5][10]; // Create the array of frames
int trackBufferFull[5] = {0, 0, 0, 0, 0};// Keeps track of how full the buffer for each node is
int trackFront[5] = {0, 0, 0, 0, 0}; // Array to keep track of which is the front of the array
int trackTail[5] = {0, 0, 0, 0, 0};


// Function to add to the array (CHANGE int frame)
void addFrame (int nodeNumber, FRAME frame)
{
//Calc tail
int tail = trackTail[nodeNumber-1];

// Calc frames in buffer
int framesinBuffer = trackBufferFull[nodeNumber-1];

if (framesinBuffer == 10)
{
printf("Buffer is full\n");
}
else
{

// Add frame to frameArray
frameArray[nodeNumber-1][tail] = frame;
printf("\nAdded a frame in node: %i to the buffer\n", nodeNumber);

// Increment the count
trackBufferFull[nodeNumber-1]++;
trackTail[nodeNumber-1] = ++trackTail[nodeNumber-1] % 10;


}
}

The arrays I use for frameArray is a wrap-around/cyclic array of length 10, hence why I have the code

trackTail[nodeNumber-1] = ++trackTail[nodeNumber-1] % 10;


Everything works perfectly in a standalone file, however when run inside of a larger file, I get the following compile errors:

$ cnet GARETH -m 30
compiling gareth.c
gareth.c: In function ‘addFrame’:
gareth.c:77:27: error: operation on ‘trackTail[nodeNumber + -0x00000000000000001]’ may be undefined [-Werror=sequence-point]
gareth.c: In function ‘removeFirstFrame’:
gareth.c:98:28: error: operation on ‘trackFront[nodeNumber + -0x00000000000000001]’ may be undefined [-Werror=sequence-point]
gareth.c:105:1: error: control reaches end of non-void function [-Werror=return-type]
cc1: all warnings being treated as errors

Line 77 is the line

trackTail[nodeNumber-1] = ++trackTail[nodeNumber-1] % 10;

Help.

To see the code with line numbers and the errors side by side, I've uploaded an image to: