alternatives should return errors

[czlowiek488]

Support plan

• is this issue currently blocking your project? (yes/no): no -> we have temporary workaround (patch-package)
• is this issue affecting a production system? (yes/no): yes

Context

• module version: 17.4.0
• environment (e.g. node, browser, native): node
• used with (e.g. hapi application, another framework, standalone, ...): enjoi, asyncapi specification

What problem are you trying to solve?

I generate validators using enjoi and asyncapi. All of validators use alternatives (its caused by asyncapi specification). My problem is that it wont return errors.

Do you have a new or modified API suggestion to solve the problem?

Im using patch-package to overwrite one file to achieve expected behaviour. Here is commit file which I use.

diff --git a/node_modules/joi/lib/types/alternatives.js b/node_modules/joi/lib/types/alternatives.js
index 875f2b0..50bd9d9 100755
--- a/node_modules/joi/lib/types/alternatives.js
+++ b/node_modules/joi/lib/types/alternatives.js
@@ -46,6 +46,7 @@ module.exports = Any.extend({
 
         if (schema._flags.match) {
             const matched = [];
+            const errors = [];
 
             for (let i = 0; i < schema.$_terms.matches.length; ++i) {
                 const item = schema.$_terms.matches[i];
@@ -57,20 +58,21 @@ module.exports = Any.extend({
                     matched.push(result.value);
                 }
                 else {
+                    errors.push(result.errors.toString());
                     localState.restore();
                 }
             }
 
             if (matched.length === 0) {
-                return { errors: error('alternatives.any') };
+                return { errors: error('alternatives.any', { errors }) };
             }
 
             if (schema._flags.match === 'one') {
-                return matched.length === 1 ? { value: matched[0] } : { errors: error('alternatives.one') };
+                return matched.length === 1 ? { value: matched[0] } : { errors: error('alternatives.one', { errors }) };
             }
 
             if (matched.length !== schema.$_terms.matches.length) {
-                return { errors: error('alternatives.all') };
+                return { errors: error('alternatives.all', { errors }) };
             }
 
             const allobj = schema.$_terms.matches.reduce((acc, v) => acc && v.schema.type === 'object', true);