Double-escape back-slashes (#11)

* keep require.resolve for runtime.js

* use path.resolve

* replace backslash with double backslash

Author: mfix-stripe

src/loader.js

@@ -4,6 +4,10 @@ const Markdoc = require('@markdoc/markdoc');
 
 const DEFAULT_SCHEMA_PATH = './markdoc';
 
+function normalize(s) {
+  return s.replace(/\\/g, '\\\\');
+}
+
 async function gatherPartials(ast, schemaDir) {
   let partials = {};
 
@@ -128,7 +132,7 @@ async function load(source) {
     async function readDir(variable) {
       try {
         const module = await resolve(schemaDir, variable);
-        return `import * as ${variable} from '${module}'`;
+        return `import * as ${variable} from '${normalize(module)}'`;
       } catch (error) {
         return `const ${variable} = {};`;
       }
@@ -162,7 +166,7 @@ import yaml from 'js-yaml';
 // renderers is imported separately so Markdoc isn't sent to the client
 import Markdoc, {renderers} from '@markdoc/markdoc'
 
-import {getSchema} from '${await resolve(__dirname, './runtime')}';
+import {getSchema} from '${normalize(await resolve(__dirname, './runtime'))}';
 /**
  * Schema is imported like this so end-user's code is compiled using build-in babel/webpack configs.
  * This enables typescript/ESnext support