From 5d6d5ed7c9e2c0663f3ea473c7190b579a8a6dad Mon Sep 17 00:00:00 2001
From: Eran Hammer <eran@hammer.io>
Date: Sat, 28 Sep 2019 21:37:14 -0700
Subject: [PATCH] Fix error() function. Closes #2147

---
 lib/validator.js | 4 ++++
 test/base.js     | 9 +++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/validator.js b/lib/validator.js
index 3a6e22d0a..8891b768e 100755
--- a/lib/validator.js
+++ b/lib/validator.js
@@ -461,6 +461,10 @@ internals.finalize = function (value, errors, helpers) {
             if (!Array.isArray(errors)) {
                 errors = [errors];
             }
+
+            for (const error of errors) {
+                Assert(error instanceof Error || error instanceof Errors.Report, 'error() must return an Error object');
+            }
         }
         else {
             errors = [schema._flags.error];
diff --git a/test/base.js b/test/base.js
index 6f2d0ecad..d31f73b55 100755
--- a/test/base.js
+++ b/test/base.js
@@ -1372,7 +1372,6 @@ describe('any', () => {
                     }
                 });
             }).to.throw('Must provide a valid Error object or a function');
-
         });
 
         it('errors on missing error option', () => {
@@ -1386,7 +1385,6 @@ describe('any', () => {
                     }
                 });
             }).to.throw('Missing error');
-
         });
 
         describe('with a function', () => {
@@ -1540,6 +1538,13 @@ describe('any', () => {
                 expect(result2.value).to.equal({ a: [' xx', 'yy?'], b: ' x' });
                 expect(result2.error).to.be.an.error('my new error message');
             });
+
+            it('errors on invalid error function', () => {
+
+                const schema = Joi.number().error(() => 'not an Error');
+
+                expect(() => schema.validate('x')).to.throw('error() must return an Error object');
+            });
         });
     });