From 974da05ceb163b456e9296e3e8b327655cb922f8 Mon Sep 17 00:00:00 2001
From: Bhavy Singhal <debug.bhavysinghal@gmail.com>
Date: Sat, 30 May 2026 15:11:00 +0530
Subject: [PATCH] Improve history file format error message

---
 CHANGELOG.md                    | 7 +++++++
 src/archivist/services/index.js | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc6c0feb9..d39b987cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 All changes that impact users of this module are documented in this file, in the [Common Changelog](https://common-changelog.org) format with some additional specifications defined in the CONTRIBUTING file. This codebase adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased [patch]
+
+> Development of this release was made on a volunteer basis by Bhavy Singhal.
+
+### Fixed
+- Improve error message when history file is wrongly formatted as an object instead of an array
+
 ## 12.0.2 - 2026-05-26
 
 > Development of this release was supported by [User Rights](https://www.user-rights.org).
diff --git a/src/archivist/services/index.js b/src/archivist/services/index.js
index 980973379..2e7c8a229 100644
--- a/src/archivist/services/index.js
+++ b/src/archivist/services/index.js
@@ -260,6 +260,9 @@ async function loadServiceHistoryFiles(serviceId) {
   ]);
 
   Object.entries(serviceDeclaration.terms).forEach(([ termsType, declaration ]) => {
+    if (!Array.isArray(serviceHistory[termsType]) && serviceHistory[termsType] !== undefined) {
+      throw new Error(`History file for "${termsType}" is not properly formatted: expected an array but got an object. Please use [] instead of {}.`);
+    }
     serviceHistory[termsType] = serviceHistory[termsType] || [];
     serviceHistory[termsType].push(declaration);
   });