add hw2

node_modules/commander/lib/error.js

@@ -0,0 +1,39 @@
+/**
+ * CommanderError class
+ */
+class CommanderError extends Error {
+  /**
+   * Constructs the CommanderError class
+   * @param {number} exitCode suggested exit code which could be used with process.exit
+   * @param {string} code an id string representing the error
+   * @param {string} message human-readable description of the error
+   */
+  constructor(exitCode, code, message) {
+    super(message);
+    // properly capture stack trace in Node.js
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+    this.code = code;
+    this.exitCode = exitCode;
+    this.nestedError = undefined;
+  }
+}
+
+/**
+ * InvalidArgumentError class
+ */
+class InvalidArgumentError extends CommanderError {
+  /**
+   * Constructs the InvalidArgumentError class
+   * @param {string} [message] explanation of why argument is invalid
+   */
+  constructor(message) {
+    super(1, 'commander.invalidArgument', message);
+    // properly capture stack trace in Node.js
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+  }
+}
+
+exports.CommanderError = CommanderError;
+exports.InvalidArgumentError = InvalidArgumentError;