handle case when no snapshot can be created in ResolverCachePlugin

lib/cache/ResolverCachePlugin.js

@@ -170,6 +170,10 @@ class ResolverCachePlugin {
 						null,
 						(err, snapshot) => {
 							if (err) return callback(err);
+							if (!snapshot) {
+								if (result) return callback(null, result);
+								return callback();
+							}
 							cache.store(
 								identifier,
 								null,

test/WatchTestCases.test.js

@@ -7,6 +7,7 @@ const rimraf = require("rimraf");
 const checkArrayExpectation = require("./checkArrayExpectation");
 const createLazyTestEnv = require("./helpers/createLazyTestEnv");
 const { remove } = require("./helpers/remove");
+const prepareOptions = require("./helpers/prepareOptions");
 
 const webpack = require("..");
 
@@ -114,7 +115,12 @@ describe("WatchTestCases", () => {
 
 							let options = {};
 							const configPath = path.join(testDirectory, "webpack.config.js");
-							if (fs.existsSync(configPath)) options = require(configPath);
+							if (fs.existsSync(configPath)) {
+								options = prepareOptions(require(configPath), {
+									testPath: outputDirectory,
+									srcPath: tempDirectory
+								});
+							}
 							const applyConfig = options => {
 								if (!options.mode) options.mode = "development";
 								if (!options.context) options.context = tempDirectory;

test/watchCases/snapshot/unable-to-snapshot/0/index.js

@@ -0,0 +1,5 @@
+import value from "package";
+
+it("should not crash", () => {
+	expect(value).toBe(42 + WATCH_STEP);
+});

test/watchCases/snapshot/unable-to-snapshot/0/node_modules/package/changing-file.js

@@ -0,0 +1 @@
+module.exports = "0";

test/watchCases/snapshot/unable-to-snapshot/0/node_modules/package/index.js

@@ -0,0 +1,2 @@
+import other from "./changing-file";
+export default 42 + other;

test/watchCases/snapshot/unable-to-snapshot/1/node_modules/package/changing-file.js

@@ -0,0 +1 @@
+module.exports = "1";

test/watchCases/snapshot/unable-to-snapshot/2/node_modules/package/changing-file.js

@@ -0,0 +1 @@
+module.exports = "2";

test/watchCases/snapshot/unable-to-snapshot/webpack.config.js

@@ -0,0 +1,8 @@
+const path = require("path");
+/** @type {function(any, any): import("../../../../").Configuration} */
+module.exports = (env, { srcPath }) => ({
+	cache: {
+		type: "memory",
+		managedPaths: [path.resolve(srcPath, "node_modules")]
+	}
+});