fix(docz-core): use user-provided 404 page when it exists

Looks in ${themesDir}/pages/
which defaults to src/pages/

core/docz-core/src/bundler/machine/actions.ts

@@ -19,6 +19,7 @@ const ensureFile = (filename: string, toDelete?: string) => {
 }
 
 export const ensureFiles = ({ args }: ServerMachineCtx) => {
+  // themesDir defaults to "src" to behave like a normal gatsby site
   const appPath = path.join(paths.root, args.themesDir)
   const themeNames = glob.sync('gatsby-theme-**', {
     cwd: appPath,
@@ -30,6 +31,13 @@ export const ensureFiles = ({ args }: ServerMachineCtx) => {
       path.join(paths.docz, 'src', themeName)
     )
   })
+  const userPagesPath = path.join(appPath, 'pages')
+  const doczPagesPath = path.join(paths.docz, 'src', 'pages')
+  // Copy 404 and other possible Gatsby pages
+  if (fs.existsSync(userPagesPath)) {
+    fs.copySync(userPagesPath, doczPagesPath)
+  }
+
   copyDoczRc(args.config)
   ensureFile('gatsby-browser.js')
   ensureFile('gatsby-ssr.js')

core/docz-core/src/bundler/machine/services/create-resources.ts

@@ -80,8 +80,10 @@ const copyEslintIgnore = async () => {
   }
 }
 
-export const writeNotFound = async () => {
+export const writeDefaultNotFound = async () => {
   const outputPath = path.join(paths.docz, 'src/pages/404.js')
+  // If it exists then it would have been created in ensureFiles while copying the theme
+  if (fs.existsSync(outputPath)) return
   await outputFileFromTemplate('404.tpl.js', outputPath, {})
 }
 
@@ -132,7 +134,7 @@ export const createResources = async (ctx: ServerMachineCtx) => {
     await copyAndModifyPkgJson(ctx)
     await writeEslintRc()
     await copyEslintIgnore()
-    await writeNotFound()
+    await writeDefaultNotFound()
     await writeGatsbyConfig(ctx)
     await writeGatsbyConfigNode()
     await writeGatsbyConfigCustom()