Check some errors (not enough).

malloc can always fail. Check to avoid null dereference.

malloc(0) is well defined but leads to an eventual crash on some systems.
Check it too.

tools/pokemon_animation_graphics.c

@@ -90,8 +90,16 @@ void create_tilemap(struct Tilemap* tilemap, struct Graphic* graphic, char* grap
 	}
 	fseek(f, 0, SEEK_END);
 	graphics_size = ftell(f);
+	if (!graphics_size) {
+		fprintf(stderr, "empty file %s\n", graphics_filename);
+		exit(1);
+	}
 	rewind(f);
 	graphics = malloc(graphics_size);
+	if (!graphics) {
+		fprintf(stderr, "malloc failure\n");
+		exit(1);
+	}
 	fread(graphics, 1, graphics_size, f);
 	fclose(f);