Add Yargs default and middleware logic to display helpful message during invalid arg/command calls

bin/near-cli.js

@@ -143,6 +143,11 @@ const clean = {
     handler: exitOnError(main.clean)
 };
 
+const defaultCommand = {
+    command: '$0',
+    handler: exitOnError(main.defaultCommand)
+};
+
 let config = require('../get-config')();
 yargs // eslint-disable-line
     .middleware(require('../utils/check-version'))
@@ -191,6 +196,7 @@ yargs // eslint-disable-line
     .command(login)
     .command(require('../commands/repl'))
     .command(require('../commands/generate-key'))
+    .command(defaultCommand)
     .config(config)
     .alias({
         'accountId': ['account_id'],

index.js

@@ -121,3 +121,19 @@ exports.stake = async function(options) {
     const result = await account.stake(options.stakingKey, utils.format.parseNearAmount(options.amount));
     console.log(inspectResponse(result));
 };
+
+exports.defaultCommand = async function(options) {
+    let unclearPiece = `'${options._.join(', ')}'`;
+    switch (options._.length) {
+    case 0:
+        unclearPiece = 'argument(s)';
+        break;
+    case 1:
+        unclearPiece = `'${options._}'`;
+        break;
+    default:
+        // use initialized value
+        break;
+    }
+    console.warn(`Sorry, I do not understand ${unclearPiece}\nPlease run 'near' to see the list of available commands.`);
+};