Altra conversione in Typescript , partendo da un progetto di esempio funzionante...

src/views/Error404.vue

@@ -0,0 +1,58 @@
+<template>
+  <div class="error-page window-height window-width bg-light column items-center">
+    <div class="error-code bg-primary flex items-center justify-center">
+      404
+    </div>
+    <div>
+      <div class="error-card card bg-white column items-center justify-center">
+        <i class="text-grey-5">error_outline</i>
+        <p class="caption text-center">Oops. Nothing here...</p>
+        <p class="text-center group">
+          <button v-if="canGoBack" class="grey push small" @click="goBack">
+            <i class="on-left">keyboard_arrow_left</i>
+            Go back
+          </button>
+          <router-link to="/">
+            <button class="grey push small">
+              Go home
+              <i class="on-right">home</i>
+            </button>
+          </router-link>
+        </p>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script type="text/javascript">
+export default {
+  data () {
+    return {
+      canGoBack: window.history.length > 1
+    }
+  },
+  methods: {
+    goBack () {
+      window.history.go(-1)
+    }
+  }
+}
+</script>
+
+<style lang="stylus">
+.error-page
+  .error-code
+    height 50vh
+    width 100%
+    padding-top 15vh
+    font-size 30vmax
+    color rgba(255, 255, 255, .2)
+    overflow hidden
+  .error-card
+    margin-top -25px
+    width 90vw
+    max-width 600px
+    padding 50px
+    i
+      font-size 5rem
+</style>