parameters: avoid printing errors for erased flash devices

Errors:
ERROR [parameters] param import failed (-1) attempt 1, retrying
ERROR [parameters] param import failed (-1) attempt 2, retrying
ERROR [parameters] param import failed (-1) attempt 3, retrying
ERROR [parameters] param import failed (-1) attempt 4, retrying
ERROR [param] importing from '/fs/mtd_caldata' failed (-1)

src/lib/parameters/parameters.cpp

@@ -1426,6 +1426,10 @@ param_import_internal(int fd, bool mark_saved)
 					 decoder.total_decoded_size);
 				return 0;
 
+			} else if (result == -ENODATA) {
+				PX4_DEBUG("BSON: no data");
+				return 0;
+
 			} else {
 				PX4_ERR("param import failed (%d) attempt %d, retrying", result, attempt);
 			}

src/lib/parameters/tinybson/tinybson.cpp

@@ -134,7 +134,7 @@ bson_decoder_init_file(bson_decoder_t decoder, int fd, bson_decoder_callback cal
 		CODER_KILL(decoder, "failed reading length");
 	}
 
-	debug("total document size = %d", decoder->total_document_size);
+	debug("total document size = %" PRIi32, decoder->total_document_size);
 
 	/* ready for decoding */
 	return 0;
@@ -176,7 +176,7 @@ bson_decoder_init_buf(bson_decoder_t decoder, void *buf, unsigned bufsize, bson_
 		CODER_KILL(decoder, "failed reading length");
 	}
 
-	debug("total document size = %d", decoder->total_document_size);
+	debug("total document size = %" PRIi32, decoder->total_document_size);
 
 	if ((decoder->total_document_size > 0) && (decoder->total_document_size > (int)decoder->bufsize)) {
 		CODER_KILL(decoder, "document length larger than buffer");
@@ -235,6 +235,10 @@ bson_decoder_next(bson_decoder_t decoder)
 	if (decoder->node.type == BSON_EOO) {
 		decoder->node.name[0] = '\0';
 
+	} else if ((int)decoder->node.type == 0xff) { // indicates erased FLASH
+		decoder->dead = true;
+		return -ENODATA;
+
 	} else {
 
 		/* get the node name */
@@ -526,7 +530,7 @@ bson_encoder_fini(bson_encoder_t encoder)
 	// record document size
 	if (encoder->fd > -1) {
 		if (lseek(encoder->fd, 0, SEEK_SET) == 0) {
-			debug("writing document size %d to beginning of file", encoder->total_document_size);
+			debug("writing document size %" PRIi32 " to beginning of file", encoder->total_document_size);
 
 			if (::write(encoder->fd, &encoder->total_document_size,
 				    sizeof(encoder->total_document_size)) != sizeof(encoder->total_document_size)) {