prevent reading directories as files when building fs cache webpack#1…

…6417

Looks like a nodejs bug, introduced in v23.0.0 - commit hash 00b2f07f
It should be fixed in v23.2.0 - dd9b6833

bug: nodejs/node#54160
fix: nodejs/node#55527

I am able to replicate this on v23.1.0.

lib/FileSystemInfo.js

@@ -3265,34 +3265,44 @@ class FileSystemInfo {
 	 * @private
 	 */
 	_readFileHash(path, callback) {
-		this.fs.readFile(path, (err, content) => {
+		this.fs.stat(path, (err, _stat) => {
 			if (err) {
-				if (err.code === "EISDIR") {
-					this._fileHashes.set(path, "directory");
-					return callback(null, "directory");
-				}
 				if (err.code === "ENOENT") {
 					this._fileHashes.set(path, null);
 					return callback(null, null);
 				}
-				if (err.code === "ERR_FS_FILE_TOO_LARGE") {
-					/** @type {Logger} */
-					(this.logger).warn(`Ignoring ${path} for hashing as it's very large`);
-					this._fileHashes.set(path, "too large");
-					return callback(null, "too large");
-				}
 				return callback(/** @type {WebpackError} */ (err));
 			}
 
-			const hash = createHash(this._hashFunction);
+			const stat = /** @type {IStats} */ (_stat);
+			if (stat.isDirectory()) {
+				this._fileHashes.set(path, "directory");
+				return callback(null, "directory");
+			}
+
+			this.fs.readFile(path, (err, content) => {
+				if (err) {
+					if (err.code === "ERR_FS_FILE_TOO_LARGE") {
+						/** @type {Logger} */
+						(this.logger).warn(
+							`Ignoring ${path} for hashing as it's very large`
+						);
+						this._fileHashes.set(path, "too large");
+						return callback(null, "too large");
+					}
+					return callback(/** @type {WebpackError} */ (err));
+				}
+
+				const hash = createHash(this._hashFunction);
 
-			hash.update(/** @type {string | Buffer} */ (content));
+				hash.update(/** @type {string | Buffer} */ (content));
 
-			const digest = /** @type {string} */ (hash.digest("hex"));
+				const digest = /** @type {string} */ (hash.digest("hex"));
 
-			this._fileHashes.set(path, digest);
+				this._fileHashes.set(path, digest);
 
-			callback(null, digest);
+				callback(null, digest);
+			});
 		});
 	}