diff --git a/screenshot/errorHandler.js b/screenshot/errorHandler.js
new file mode 100644
index 00000000..3db9a79b
--- /dev/null
+++ b/screenshot/errorHandler.js
@@ -0,0 +1,6 @@
+// A little utility to catch errors executing the test generation routines
+
+window.addEventListener('error', errorMsg => {
+	window.__TEST_DATA = 'Error occurred: ' + errorMsg.message;
+	return false;
+}, {capture: true});
diff --git a/screenshot/index.js b/screenshot/index.js
index 1f615aa5..e8e5d33e 100644
--- a/screenshot/index.js
+++ b/screenshot/index.js
@@ -1,5 +1,6 @@
 import {render} from 'react-dom';
 import App, {testMetadata} from 'UI_TEST_APP_ENTRY';
+import './errorHandler';
 import TestChooser from './TestChooser';
 
 const url = new URL(window.location.href);
diff --git a/utils/runTest.js b/utils/runTest.js
index 970bdabe..a5ade2e4 100644
--- a/utils/runTest.js
+++ b/utils/runTest.js
@@ -20,6 +20,10 @@ const runTest = ({concurrency, filter, Page, testName, ...rest}) => {
 				return window.__TEST_DATA; // eslint-disable-line no-undef
 			});
 
+			if (typeof testCases === 'string') {
+				throw new Error(`Test data failed to load: ${testCases}.\n\nLoad page in a browser to view the error.`)
+			}
+
 			expect(testCases).to.be.an('object', 'Test data failed to load');
 
 			describe(testName, function () {