first implementation

frontend/node_modules/vue-demi/lib/index.mjs

@@ -0,0 +1,34 @@
+import * as Vue from 'vue'
+
+var isVue2 = false
+var isVue3 = true
+var Vue2 = undefined
+
+function install() {}
+
+export function set(target, key, val) {
+  if (Array.isArray(target)) {
+    target.length = Math.max(target.length, key)
+    target.splice(key, 1, val)
+    return val
+  }
+  target[key] = val
+  return val
+}
+
+export function del(target, key) {
+  if (Array.isArray(target)) {
+    target.splice(key, 1)
+    return
+  }
+  delete target[key]
+}
+
+export * from 'vue'
+export {
+  Vue,
+  Vue2,
+  isVue2,
+  isVue3,
+  install,
+}