Reduce memory footprint of storing fs erros in cache

lib/CachedInputFileSystem.js

@@ -368,6 +368,19 @@ class CacheBackend {
 	 */
 	_storeResult(path, err, result) {
 		if (this._data.has(path)) return;
+
+		if (err) {
+			// Clone error object to be stored in cache to allow for the original
+			// error, and its internal representation to be picked up by GC. Thus
+			// reducing the memory footprint of caching such results in memory.
+			// Also, omitting expensive calculation of the stacktrace as it gets
+			// ignored most of the time anyway
+			const lightErrorProps = Object.getOwnPropertyDescriptors(err);
+			delete lightErrorProps.stack;
+
+			err = Object.create(Object.getPrototypeOf(err), lightErrorProps);
+		}
+
 		const level = this._levels[this._currentLevel];
 		this._data.set(path, { err, result, level });
 		level.add(path);