feature: log options validations errors in CLI

Ajv is using doT to compile validation logic. There is minimal overhead validating an object against a pre-compiled schema. In case of the CLI, options will be validated once by the CLI engine and the second time by API.

I prefer to explicitly handle error checking rather than relying on an error getting thrown by the API engine.

API needs to retain “validationErrors” object nevertheless to enable debugging when using webpack programmatically.

bin/convert-argv.js

@@ -4,6 +4,7 @@ fs.existsSync = fs.existsSync || path.existsSync;
 var resolve = require("enhanced-resolve");
 var interpret = require("interpret");
 var WebpackOptionsDefaulter = require("../lib/WebpackOptionsDefaulter");
+var validateWebpackOptions = require("../lib/validateWebpackOptions");
 
 module.exports = function(optimist, argv, convertOptions) {
 
@@ -553,5 +554,11 @@ module.exports = function(optimist, argv, convertOptions) {
 			console.error("Use --help to display the CLI options.");
 			process.exit(-1); // eslint-disable-line
 		}
+		var webpackOptionsValidationErrors = validateWebpackOptions(options);
+
+		if (webpackOptionsValidationErrors.length) {
+			console.error("Configuration is invalid. Fix the following errors:", webpackOptionsValidationErrors);
+			process.exit(-1); // eslint-disable-line
+		}
 	}
 };