From 4571f756b88cc4ca50d884aadba90ca43c21acad Mon Sep 17 00:00:00 2001
From: Utkarsh Bhatnagar <utkarsh.cmu@gmail.com>
Date: Wed, 12 Aug 2026 07:21:25 -0700
Subject: [PATCH] fix(ui): tolerate non-JSON AnalysisRun measurement values

Argo Rollouts' web provider passes a plain text response body through
unchanged, so a measurement value is not guaranteed to be JSON.
transformMeasurementValue called JSON.parse without a guard, which threw a
SyntaxError and stopped the analysis modal from rendering at all -- clicking
an AnalysisRun under a Stage's Verifications tab failed with
"SyntaxError: Unexpected token 'P', \"PASS\" is not valid JSON".

Treat an unparseable value as a non-chartable table value, consistent with
how the function already handles unsupported formats.

Signed-off-by: Utkarsh Bhatnagar <utkarsh.cmu@gmail.com>
---
 .../common/analysis-modal/transforms.test.ts  | 42 ++++++++++++++++++-
 .../common/analysis-modal/transforms.ts       | 14 ++++++-
 2 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/ui/src/features/common/analysis-modal/transforms.test.ts b/ui/src/features/common/analysis-modal/transforms.test.ts
index e3750a498f..f97428bc27 100644
--- a/ui/src/features/common/analysis-modal/transforms.test.ts
+++ b/ui/src/features/common/analysis-modal/transforms.test.ts
@@ -24,7 +24,8 @@ import {
   metricStatusLabel,
   metricSubstatus,
   printableCloudWatchQuery,
-  printableDatadogQuery
+  printableDatadogQuery,
+  transformMeasurements
 } from './transforms';
 import { AnalysisStatus, FunctionalStatus } from './types';
 
@@ -559,4 +560,43 @@ describe('analysis modal transforms', () => {
       tableValue: { latency: null, cpuUsage: null }
     });
   });
+
+  // Regression: a provider that returns plain text (the web provider passes a
+  // text/plain body through unchanged) used to throw a SyntaxError out of
+  // JSON.parse and take the whole analysis modal down with it.
+  test('transformMeasurements() with a plain text measurement value', () => {
+    expect(transformMeasurements([], [{ value: 'PASS' }])).toEqual({
+      chartable: false,
+      min: 0,
+      max: null,
+      measurements: [{ value: 'PASS', chartValue: null, tableValue: 'PASS' }]
+    });
+  });
+  test('transformMeasurements() with a malformed JSON measurement value', () => {
+    expect(transformMeasurements([], [{ value: '{"cpuUsage":' }])).toEqual({
+      chartable: false,
+      min: 0,
+      max: null,
+      measurements: [{ value: '{"cpuUsage":', chartValue: null, tableValue: '{"cpuUsage":' }]
+    });
+  });
+  test('transformMeasurements() still parses a valid JSON measurement value', () => {
+    expect(transformMeasurements([], [{ value: '500' }])).toEqual({
+      chartable: true,
+      min: 0,
+      max: 500,
+      measurements: [{ value: '500', chartValue: 500, tableValue: 500 }]
+    });
+  });
+  test('transformMeasurements() with both parseable and unparseable values', () => {
+    expect(transformMeasurements([], [{ value: '500' }, { value: 'PASS' }])).toEqual({
+      chartable: false,
+      min: 0,
+      max: 500,
+      measurements: [
+        { value: '500', chartValue: 500, tableValue: 500 },
+        { value: 'PASS', chartValue: null, tableValue: 'PASS' }
+      ]
+    });
+  });
 });
diff --git a/ui/src/features/common/analysis-modal/transforms.ts b/ui/src/features/common/analysis-modal/transforms.ts
index 046ef4f86e..9bec6b9f6a 100644
--- a/ui/src/features/common/analysis-modal/transforms.ts
+++ b/ui/src/features/common/analysis-modal/transforms.ts
@@ -783,7 +783,19 @@ const transformMeasurementValue = (
     };
   }
 
-  const parsedValue = JSON.parse(value);
+  let parsedValue;
+  try {
+    parsedValue = JSON.parse(value);
+  } catch {
+    // Providers are not obliged to return JSON. The web provider, for one,
+    // passes a plain text response through untouched. Such a value cannot be
+    // charted, but it is still worth surfacing in the table as-is.
+    return {
+      canChart: false,
+      chartValue: null,
+      tableValue: value
+    };
+  }
 
   // single number measurement value
   if (isFiniteNumber(parsedValue)) {