fix(contentHash): Prevent generation of a contentHash when the set of modules is of size 0

Author: danhcanva

src/index.js

@@ -786,7 +786,7 @@ class MiniCssExtractPlugin {
           compilation.runtimeTemplate.requestShortener,
         );
 
-        if (modules) {
+        if (modules?.size > 0) {
           const { hashFunction, hashDigest, hashDigestLength } = outputOptions;
           const { createHash } = compiler.webpack.util;
           const hash = createHash(/** @type {string} */ (hashFunction));