Go back to alpha.3, alpha.4 doesn't seem to work (API change?).

package.json

@@ -5,10 +5,10 @@
     "build": "webpack --env.prod"
   },
   "dependencies": {
-    "vue": "^3.0.0-alpha.4"
+    "vue": "^3.0.0-alpha.3"
   },
   "devDependencies": {
-    "@vue/compiler-sfc": "^3.0.0-alpha.4",
+    "@vue/compiler-sfc": "^3.0.0-alpha.3",
     "css-loader": "^3.4.2",
     "file-loader": "^5.0.2",
     "mini-css-extract-plugin": "^0.9.0",

yarn.lock

@@ -31,29 +31,29 @@
   resolved "https://registry.yarnpkg.com/@types/node/-/node-12.12.21.tgz#aa44a6363291c7037111c47e4661ad210aded23f"
   integrity sha512-8sRGhbpU+ck1n0PGAUgVrWrWdjSW2aqNeyC15W88GRsMpSwzv6RJGlLhE7s2RhVSOdyDmxbqlWSeThq4/7xqlA==
 
-"@vue/compiler-core@3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/compiler-core/-/compiler-core-3.0.0-alpha.4.tgz#46d62d0fa70495e0fb3d23dd7b4c57fb4344f410"
-  integrity sha512-WiRK3LSW4N+L8snXMx9aNANBO1LTlfIPf+2M6ld0GZEsiGj0JNJIheXPYdhSCjRNSIU5GqLFxWvzNgGGN9e4DQ==
+"@vue/compiler-core@3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/compiler-core/-/compiler-core-3.0.0-alpha.3.tgz#632dd4217e0490aa6aa2c8d2c3956045972b8bd9"
+  integrity sha512-xzqlzor8zZXvhfputSUTXlKZ7RT+w8ro9PjDDMOfgRNrdhRLAOUSULvLKh6fB1zMZiBPUYpX/WuAqB5+7ZXARw==
   dependencies:
     acorn "^7.1.0"
     estree-walker "^0.8.1"
     source-map "^0.6.1"
 
-"@vue/compiler-dom@3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/compiler-dom/-/compiler-dom-3.0.0-alpha.4.tgz#638141bb293f09692f005e8da46bdb64ac680fec"
-  integrity sha512-QtDs/ezMMYcIX5gN9qijmTQE5YcOQH4TH/PKZUdToe0bjDQEhAaMiedKfTrLjR+OTxuHkFvayp4SzUzTiQ3CAQ==
+"@vue/compiler-dom@3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/compiler-dom/-/compiler-dom-3.0.0-alpha.3.tgz#e4844edfddefefd9661ebce2666d865d49c77397"
+  integrity sha512-m87mvZoYyE1HF3yNfl8qBxr6xqNeV4XSe/zneb+0tZNp5RyTTi9Kg8tnPZZ65HYBaX5huRxO66DAf1eb2O9Nfg==
   dependencies:
-    "@vue/compiler-core" "3.0.0-alpha.4"
+    "@vue/compiler-core" "3.0.0-alpha.3"
 
-"@vue/compiler-sfc@^3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/compiler-sfc/-/compiler-sfc-3.0.0-alpha.4.tgz#5013249b00f5c81ee1f247bc1b128f3233af4f96"
-  integrity sha512-JlER3RUHC8seCMHV3dZgqDf48IrEGZ6HKrCWOi/ed3N825pJQAgmwJBe5XkPKNMmFBjiWypT4NYAkBU0YbLkhg==
+"@vue/compiler-sfc@^3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/compiler-sfc/-/compiler-sfc-3.0.0-alpha.3.tgz#5e1c8fd5dda5b8d8075140a547afb146225fd382"
+  integrity sha512-TmeS2xugaibC4XQqqMPeb7vyfMEoIVKepuI6nh7Ad54Mm1yl48eit3XJMoBUbKzSz6rrOw8ECvKoANu1WZFAmg==
   dependencies:
-    "@vue/compiler-core" "3.0.0-alpha.4"
-    "@vue/compiler-dom" "3.0.0-alpha.4"
+    "@vue/compiler-core" "3.0.0-alpha.3"
+    "@vue/compiler-dom" "3.0.0-alpha.3"
     consolidate "^0.15.1"
     hash-sum "^2.0.0"
     lru-cache "^5.1.1"
@@ -62,24 +62,24 @@
     postcss-selector-parser "^6.0.2"
     source-map "^0.6.1"
 
-"@vue/reactivity@3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/reactivity/-/reactivity-3.0.0-alpha.4.tgz#ed09062693a03417ffc909212b3b94fd43c82569"
-  integrity sha512-ti94RMI3gccPf5Oi8ld32DaZ/7MZPYutVs80jPBoSRjb5O0byDdsE89o1HCkNI5fUNQRBkx9/N4vBEeEQamaWw==
+"@vue/reactivity@3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/reactivity/-/reactivity-3.0.0-alpha.3.tgz#6056cff882b7d4c2d3fe280622b719d9d36df97d"
+  integrity sha512-quBlbMa3rOW3ivtDbrgP2PXbkzexS5c59HL/Y9CvDY7HXilq3VcDxudqvvPzIMpvSt7eym7hU6iQiJ1cAtjp1Q==
 
-"@vue/runtime-core@3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/runtime-core/-/runtime-core-3.0.0-alpha.4.tgz#379ff0597e71270bdf8e2becf180b3cf085a36dd"
-  integrity sha512-ytC9+fPLY9PhDmdRa9hLs96ct6fOWhLEB0o3495/3WqpJEbQwleXjcYjn7j8yv3u/r+bmtiM9kqc6Hi9FOrxkA==
+"@vue/runtime-core@3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/runtime-core/-/runtime-core-3.0.0-alpha.3.tgz#2c13f458a93c74a0604c59a1505e61b644571cee"
+  integrity sha512-OzNHFuaI7h9bXa3PWdhCtdJMROhwBWn90/4MLwnGL2a8+QFGfkk6ao7yN4XWWjMeIUwIjV/A/YJAAnXnHB36bg==
   dependencies:
-    "@vue/reactivity" "3.0.0-alpha.4"
+    "@vue/reactivity" "3.0.0-alpha.3"
 
-"@vue/runtime-dom@3.0.0-alpha.4":
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/@vue/runtime-dom/-/runtime-dom-3.0.0-alpha.4.tgz#be7e703bb2b12101cfe250c08e950e410fc1c92e"
-  integrity sha512-T9FxDX8pOC/YSSCbpF1SaVAizqrFNYgKNb9kKdGJlp0dxjJU/SqpAqLjpw2cF0hSy3wsT1XzWrFtWlBZFkg6+w==
+"@vue/runtime-dom@3.0.0-alpha.3":
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/@vue/runtime-dom/-/runtime-dom-3.0.0-alpha.3.tgz#7205b667115e3a058239854f87c3eb189919fbc2"
+  integrity sha512-Zyxu9TzlnVOd3RPm01ZostA1/BB1rTig0scl9HKzqoObIiFCZueRDCedFGeWDzXJbgO9Ap9fXjmtiuXGzjlKGg==
   dependencies:
-    "@vue/runtime-core" "3.0.0-alpha.4"
+    "@vue/runtime-core" "3.0.0-alpha.3"
     csstype "^2.6.8"
 
 "@webassemblyjs/ast@1.8.5":
@@ -3942,13 +3942,13 @@ vue-loader@^16.0.0-alpha.2:
     merge-source-map "^1.1.0"
     source-map "^0.6.1"
 
-vue@^3.0.0-alpha.4:
-  version "3.0.0-alpha.4"
-  resolved "https://registry.yarnpkg.com/vue/-/vue-3.0.0-alpha.4.tgz#c0aa2a175820cb52dde4ca3e1b659df44ff5b2a5"
-  integrity sha512-hQ8bwl5tneFHjlomZ7DcwUZoB4yseM+6phOhjBQciKmPp2sYapGHNHB1O3pl/2IUFD/RtrGeZtI7BiHk9wfxxA==
+vue@^3.0.0-alpha.3:
+  version "3.0.0-alpha.3"
+  resolved "https://registry.yarnpkg.com/vue/-/vue-3.0.0-alpha.3.tgz#f7eea63de0a45e367a60f4f664ba86ff1003dbf8"
+  integrity sha512-FXK5MNIuXX9fYLFgxjeQvDaBF323OUGB2/i3nSkDt+tXUyDlmxg4kXL0DuIpPZ5EF1uERUqAeoKtZXnKrpudFg==
   dependencies:
-    "@vue/compiler-dom" "3.0.0-alpha.4"
-    "@vue/runtime-dom" "3.0.0-alpha.4"
+    "@vue/compiler-dom" "3.0.0-alpha.3"
+    "@vue/runtime-dom" "3.0.0-alpha.3"
 
 watchpack@^1.6.0:
   version "1.6.0"