Add error handling and optimize FileIO::doBuffer() in the Bridge library

Update FileIO::doBuffer() to check for TRANSFER_TIMEOUT and set buffered to 0, and optimize by incrementing readPos instead of moving all of the data one byte to the left in the buffer to skip the error code byte.

Author: bobh66

libraries/Bridge/src/FileIO.cpp

@@ -119,12 +119,15 @@ void File::doBuffer() {
   // Try to buffer up to BUFFER_SIZE characters
   readPos = 0;
   uint8_t cmd[] = {'G', handle, BUFFER_SIZE - 1};
-  buffered = bridge.transfer(cmd, 3, buffer, BUFFER_SIZE) - 1;
+  buffered = bridge.transfer(cmd, 3, buffer, BUFFER_SIZE);
   //err = buff[0]; // First byte is error code
-  if (buffered > 0) {
-    // Shift the reminder of buffer
-    for (uint8_t i = 0; i < buffered; i++)
-      buffer[i] = buffer[i + 1];
+  if (BridgeClass::TRANSFER_TIMEOUT == buffered || 0 == buffered) {
+    // transfer failed to retrieve any data
+    buffered = 0;
+  } else {
+    // transfer retrieved at least one byte of data so skip the error code character
+    readPos++;
+    buffered--;
   }
 }