chore: fix single icon case

Author: RomanHotsiy

packages/gatsby-plugin-manifest/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@redocly/gatsby-plugin-manifest",
   "description": "Gatsby plugin which adds a manifest.webmanifest to make sites progressive web apps",
-  "version": "3.3.0",
+  "version": "3.3.2",
   "author": "Kyle Mathews <mathews.kyle@gmail.com>",
   "bugs": {
     "url": "https://github.com/gatsbyjs/gatsby/issues"
@@ -13,14 +13,14 @@
     "semver": "^7.3.2"
   },
   "optionalDependencies": {
-    "sharp": "^0.28.0"
+    "sharp": "^0.27.2"
   },
   "devDependencies": {
     "@babel/cli": "^7.12.1",
     "@babel/core": "^7.12.3",
     "babel-preset-gatsby-package": "^1.3.0",
     "cross-env": "^7.0.3",
-    "sharp": "^0.28.0"
+    "sharp": "^0.27.2"
   },
   "homepage": "https://github.com/gatsbyjs/gatsby/tree/master/packages/gatsby-plugin-manifest#readme",
   "keywords": [

packages/gatsby-plugin-manifest/src/gatsby-node.js

@@ -13,14 +13,15 @@ function getSharp() {
     sharp = require(`./safe-sharp`)
     sharp.simd(true)
   }
+
+  // Handle Sharp's concurrency based on the Gatsby CPU count
+  // See: http://sharp.pixelplumbing.com/en/stable/api-utility/#concurrency
+  // See: https://www.gatsbyjs.org/docs/multi-core-builds/
+  sharp.concurrency(cpuCoreCount())
+
   return sharp
 }
 
-// Handle Sharp's concurrency based on the Gatsby CPU count
-// See: http://sharp.pixelplumbing.com/en/stable/api-utility/#concurrency
-// See: https://www.gatsbyjs.org/docs/multi-core-builds/
-sharp.concurrency(cpuCoreCount())
-
 async function generateIcon(icon, srcIcon) {
   const imgPath = path.join(`public`, icon.src)
 

packages/gatsby-plugin-manifest/src/gatsby-ssr.js

@@ -56,6 +56,16 @@ exports.onRenderBody = (
         )
       }
     }
+  } else if (icons.length) {
+    // otherwise use first icon as favicon.
+    headComponents.push(
+      <link
+        key={`gatsby-plugin-manifest-icon-link-png`}
+        rel="icon"
+        href={withPrefix(addDigestToPath(icons[0].src, cacheDigest, `none`))}
+        type="image/png"
+      />
+    )
   }
 
   // Add manifest link tag.