Elegantly handle missing LIDAR tiles

inputs.cc

@@ -234,9 +234,8 @@ int loadLIDAR(char *filenames)
 	}
 
 	while (indx < fc) {
-		fd = fopen(files[indx], "rb");
-
-		if (fd != NULL) {
+		if( (fd = fopen(files[indx], "rb")) == NULL )
+			return errno;
 
 		if (fgets(line, 255, fd) != NULL) {
 			pch = strtok (line," ");
@@ -332,9 +331,6 @@ int loadLIDAR(char *filenames)
 		fclose(fd);
 		if (debug)
 			fprintf(stderr, "LIDAR LOADED %d x %d\n", width, height);
-		} else {
-			return -1;
-		}
 		indx++;
 	} // filename(s)
 	IPPD=width;

main.cc

@@ -1665,17 +1665,13 @@ int main(int argc, char *argv[])
 
 	/* Load the required tiles */
 	if(lidar){
-		int err;
-
-		err = loadLIDAR(lidar_tiles);
-		if (err) {
+		if( (result = loadLIDAR(lidar_tiles)) != 0 ){
 			fprintf(stderr, "Couldn't find one or more of the "
 				"lidar files. Please ensure their paths are "
 				"correct and try again.\n");
-			exit(EXIT_FAILURE);
+			exit(result);
 		}
 
-
 		if(debug){
 			fprintf(stderr,"%.4f,%.4f,%.4f,%.4f,%d x %d\n",max_north,min_west,min_north,max_west,width,height);
 		}