diff --git a/__tests__/bundle/runTopLevelCatch.test.ts b/__tests__/bundle/runTopLevelCatch.test.ts
new file mode 100644
index 0000000..318c3e9
--- /dev/null
+++ b/__tests__/bundle/runTopLevelCatch.test.ts
@@ -0,0 +1,49 @@
+import type { FakeGithub } from './fakeGithub'
+import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest'
+
+import issueCommentEvent from '../fixtures/issues/issueCommentEvent.json'
+import { start } from './fakeGithub'
+import { token } from './helpers'
+import { runBundle } from './runBundle'
+
+vi.setConfig({ testTimeout: 30_000 })
+
+// run()'s top-level catch (src/run.ts), driven through dist/index.js. Every event handler swallows
+// its own rejections, so the only way to reach it is a throw that happens before a per-command
+// catch: handleIssueComment matches the comment body against each configured command without
+// guarding it, and a payload whose comment has no body makes that match throw a TypeError.
+describe('dist/index.js fails the run once from run()\'s top-level catch', () => {
+  let gh: FakeGithub
+
+  beforeAll(async () => {
+    gh = await start()
+  })
+  afterEach(() => gh.reset())
+  afterAll(() => gh.close())
+
+  function withoutBody(body: unknown) {
+    const payload = structuredClone(issueCommentEvent) as Record<string, any>
+    if (body === undefined)
+      delete payload.comment
+    else
+      payload.comment.body = body
+    return payload
+  }
+
+  it.each([
+    ['no comment object', undefined, 'undefined'],
+    ['a null comment body', null, 'null'],
+  ])('issue_comment with %s: exits 1 with one error and no api call', async (_name, body, kind) => {
+    const result = await runBundle({
+      eventName: 'issue_comment',
+      payload: withoutBody(body),
+      inputs: { ...token, 'prow-commands': '/assign /lgtm' },
+      apiUrl: gh.url,
+    })
+
+    expect(result.status, result.stdout).toBe(1)
+    expect(result.errors).toEqual([`Cannot read properties of ${kind} (reading 'replace')`])
+    expect(result.stdout).not.toContain('not yet supported')
+    expect(gh.requests).toEqual([])
+  })
+})