install source-map-support

package.json

@@ -37,6 +37,7 @@
     "rimraf": "^2.6.2",
     "sander": "^0.6.0",
     "serialize-javascript": "^1.4.0",
+    "source-map-support": "^0.5.3",
     "tslib": "^1.8.1",
     "url-parse": "^1.2.0",
     "wait-port": "^0.2.2",
@@ -60,7 +61,6 @@
     "rollup-plugin-json": "^2.3.0",
     "rollup-plugin-string": "^2.0.2",
     "rollup-plugin-typescript": "^0.8.1",
-    "source-map-support": "^0.5.2",
     "style-loader": "^0.19.1",
     "svelte": "^1.49.1",
     "svelte-loader": "^2.3.2",

src/middleware/index.ts

@@ -9,6 +9,9 @@ import escape_html from 'escape-html';
 import { create_routes, templates, create_compilers, create_template } from 'sapper/core.js';
 import { dest, entry, isDev, src } from '../config';
 import { Route, Template } from '../interfaces';
+import sourceMapSupport from 'source-map-support';
+
+sourceMapSupport.install();
 
 const dev = isDev();