fix(meta): prevent build failure for ios splash image when no icon is…

… used (#362)

* fix(meta): check ios launch scren for undefined before accessing proprieties

* feat(icon): display warning on console if the icon file was not found

lib/icon/module.js

@@ -63,6 +63,8 @@ async function run (pwa, _emitAssets) {
 
   // Disable module if no icon specified
   if (!options.source) {
+    // eslint-disable-next-line no-console
+    console.warn('[pwa] [icon] Icon not found in ' + path.resolve(this.options.srcDir, this.options.dir.static, options.fileName))
     return
   }
 

lib/meta/module.js

@@ -93,7 +93,7 @@ function generateMeta (pwa) {
     }
 
     // Launch Screen Image (IOS)
-    if (options.mobileAppIOS && !find(this.options.head.link, 'rel', 'apple-touch-startup-image')) {
+    if (options.mobileAppIOS && pwa._iosSplash && !find(this.options.head.link, 'rel', 'apple-touch-startup-image')) {
       this.options.head.link.push({ href: pwa._iosSplash.iphonese, media: '(device-width: 320px) and (device-height: 568px) and (-webkit-device-pixel-ratio: 2)', rel: 'apple-touch-startup-image' })
       this.options.head.link.push({ href: pwa._iosSplash.iphone6, media: '(device-width: 375px) and (device-height: 667px) and (-webkit-device-pixel-ratio: 2)', rel: 'apple-touch-startup-image' })
       this.options.head.link.push({ href: pwa._iosSplash.iphoneplus, media: '(device-width: 621px) and (device-height: 1104px) and (-webkit-device-pixel-ratio: 3)', rel: 'apple-touch-startup-image' })