Improve error message when reading invalid YAML file.

lib/util/yaml.js

@@ -2,7 +2,23 @@ const yaml = require('js-yaml');
 const fs = require('fs');
 
 function read(file) {
-    return yaml.safeLoad(fs.readFileSync(file, 'utf8'));
+    try {
+        return yaml.safeLoad(fs.readFileSync(file, 'utf8'));
+    } catch (error) {
+        if (error.name === 'YAMLException') {
+            error.message =
+                `\n\n\n` +
+                `\t====================================================================\n` +
+                `\tYour YAML file '${file}' is invalid\n` +
+                `\tUse e.g. https://jsonformatter.org/yaml-validator to find and fix the issue.\n` +
+                `\t====================================================================\n` +
+                `\n\n` +
+                error.message;
+        }
+
+
+        throw error;
+    }
 }
 
 function readIfExists(file) {