add workaround to ignore fatal errors during root paths resolving to …

…avoid a breaking change

README.md

@@ -59,6 +59,8 @@ For more examples creating different types resolvers (sync/async, context, etc)
 | mainFields               | ["main"]                    | A list of main fields in description files |
 | mainFiles                | ["index"]                   | A list of main files in directories |
 | modules                  | ["node_modules"]            | A list of directories to resolve modules from, can be absolute path or folder name |
+| roots                    | []                          | A list of directories to resolve request starting with `/` from |
+| ignoreRootsErrors        | false                       | Ignore fatal errors happening during handling of `roots` (allows to add `roots` without a breaking change) |
 | unsafeCache              | false                       | Use this cache object to unsafely cache the successful requests |
 | plugins                  | []                          | A list of additional resolve plugins which should be applied |
 | symlinks                 | true                        | Whether to resolve symlinks to their symlinked location |

lib/ResolverFactory.js

@@ -82,6 +82,9 @@ exports.createResolver = function(options) {
 	// A list of root paths
 	const roots = options.roots || [];
 
+	// Ignore errors happening when resolving roots
+	const ignoreRootsErrors = options.ignoreRootsErrors || false;
+
 	const restrictions = options.restrictions || [];
 
 	// Use this cache object to unsafely cache the successful requests
@@ -222,7 +225,14 @@ exports.createResolver = function(options) {
 	});
 	plugins.push(new ModuleKindPlugin("after-described-resolve", "raw-module"));
 	roots.forEach(root => {
-		plugins.push(new RootPlugin("after-described-resolve", root, "relative"));
+		plugins.push(
+			new RootPlugin(
+				"after-described-resolve",
+				root,
+				"relative",
+				ignoreRootsErrors
+			)
+		);
 	});
 	plugins.push(new JoinRequestPlugin("after-described-resolve", "relative"));
 

lib/RootPlugin.js

@@ -13,11 +13,13 @@ class RootPlugin {
 	 * @param {string | ResolveStepHook} source source hook
 	 * @param {Array<string>} root roots
 	 * @param {string | ResolveStepHook} target target hook
+	 * @param {boolean=} ignoreErrors ignore error during resolving of root paths
 	 */
-	constructor(source, root, target) {
+	constructor(source, root, target, ignoreErrors) {
 		this.root = root;
 		this.source = source;
 		this.target = target;
+		this._ignoreErrors = ignoreErrors;
 	}
 
 	/**
@@ -44,7 +46,20 @@ class RootPlugin {
 					obj,
 					`root path ${this.root}`,
 					resolveContext,
-					callback
+					this._ignoreErrors
+						? (err, result) => {
+								if (err) {
+									if (resolveContext.log) {
+										resolveContext.log(
+											`Ignored fatal error while resolving root path:\n${err}`
+										);
+									}
+									return callback();
+								}
+								if (result) return callback(null, result);
+								callback();
+						  }
+						: callback
 				);
 			});
 	}

test/roots.js

@@ -14,6 +14,7 @@ describe("roots", () => {
 		},
 		roots: [__dirname, fixtures],
 		fileSystem,
+		ignoreRootsErrors: true,
 		plugins: [
 			{
 				apply(resolver) {