Fix concaveman error

Author: kochizufan

.gitignore

@@ -62,3 +62,7 @@ typings/
 
 # JetBrain
 .idea
+
+# Open/Keep
+.git.keep
+.git.open

es5/index.js

@@ -1,4 +1,4 @@
-/*! @maplat/tin v0.9.0 | Kohei Otsuka, Code for History | license: Maplat Limited License 1.1 */
+/*! @maplat/tin v0.9.1 | Kohei Otsuka, Code for History | license: Maplat Limited License 1.1 */
 
 /**
    * splaytree v3.1.0

es5/index.js.LICENSE.txt

@@ -0,0 +1,14 @@
+/* eslint-disable @typescript-eslint/no-var-requires */
+/* eslint-disable no-empty */
+const gulp = require("gulp");
+const fs = require("fs-extra");
+
+gulp.task("git_keep", async () => {
+  fs.removeSync('.git');
+  fs.copySync('.git.keep', '.git');
+});
+
+gulp.task("git_open", async () => {
+  fs.removeSync('.git');
+  fs.copySync('.git.open', '.git');
+});