Fix crash from unsafe typings by gundermanc · Pull Request #24578 · google-gemini/gemini-cli

gundermanc · 2026-04-02T22:30:13Z

Summary

Fixes the following crash stack and updates typings to prevent similar issues in the future.

 ERROR  data.slice is not a function

 file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bundle/interactiveCl
 i-VLQHRXHU.js:20831:83

 -AnsiOutputTex
  t           (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bundle
              /interactiveCli-VLQHRXHU.js:20831:83)
 -react-stack-bottom-f
  rame               (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli
                     /bundle/chunk-UNM3DGTG.js:21469:20)
 -renderWithHook
  s            (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bundl
               e/chunk-UNM3DGTG.js:12599:24)
 -updateFunctionCompon
  ent                (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli
                     /bundle/chunk-UNM3DGTG.js:14922:21)
 -beginWork
          (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bundle/chu
          nk-UNM3DGTG.js:15889:20)
 -runWithFiberInDE
  V              (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bun
                 dle/chunk-UNM3DGTG.js:11521:72)
 -performUnitOfWor
  k              (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bun
                 dle/chunk-UNM3DGTG.js:19278:82)
 -workLoopSync
             (file:///Users/gundermanc/.nvm/versions/node/v20.19.6/lib/node_modules/@google/gemini-cli/bundle/
             chunk-UNM3DGTG.js:19132:43)

gemini-code-assist · 2026-04-02T22:31:21Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a runtime crash caused by unsafe array operations and improves the overall type safety of the tool result display component. It also enhances the UI by providing a fallback mechanism to render arbitrary objects as JSON, ensuring better visibility for unexpected data structures.

Highlights

Crash Fix: Added a safety check in AnsiOutputText to ensure data is an array before calling slice, preventing runtime errors.
Type Safety: Updated ToolResultDisplay to use more robust typings and removed unsafe type assertions.
Feature Enhancement: Added support for rendering unknown objects as stringified JSON in the tool result display.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	`/gemini review`	Performs a code review for the current pull request in its current state.
Pull Request Summary	`/gemini summary`	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	`/gemini help`	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

gemini-code-assist

Code Review

This pull request improves the robustness and type safety of the ToolResultDisplay and AnsiOutput components. Key changes include transitioning the resultDisplay prop to a core type, removing unsafe type assertions, and implementing a fallback to render unknown objects as stringified JSON. Review feedback highlights a critical issue where the current Array.isArray checks are too broad; since AnsiOutput expects an array of arrays, passing a flat array of strings would cause a runtime crash. It is recommended to narrow these checks to verify the nested structure of the data.

gemini-code-assist · 2026-04-02T22:34:26Z

        />
      );
-    } else {
+    } else if (Array.isArray(contentData)) {


The check Array.isArray(contentData) is too broad. If contentData is a flat array of strings (e.g., string[]), it will be passed to AnsiOutputText, which eventually calls .map() on the individual elements (expecting them to be AnsiLine arrays). This will cause a TypeError: line.map is not a function. By ensuring the first element is also an array (or the array is empty), you can safely distinguish AnsiOutput from other array types and allow them to fall through to the JSON.stringify fallback.

Suggested change

} else if (Array.isArray(contentData)) {

} else if (Array.isArray(contentData) && (contentData.length === 0 || Array.isArray(contentData[0]))) {

gemini-code-assist · 2026-04-02T22:34:26Z

@@ -178,18 +178,13 @@ export const ToolResultDisplay: React.FC<ToolResultDisplayProps> = ({
    // Virtualized path for large ANSI arrays
    if (Array.isArray(resultDisplay)) {


Similar to the check in renderContent, this condition should verify that the array contains nested arrays (ANSI lines). If a flat array is passed here, the virtualized ScrollableList will attempt to render items using AnsiLineText, leading to a crash when it tries to map over a string. Narrowing this check allows non-ANSI arrays to fall through to the standard rendering path where they can be handled by the JSON.stringify fallback.

Suggested change

if (Array.isArray(resultDisplay)) {

if (Array.isArray(resultDisplay) && (resultDisplay.length === 0 || Array.isArray(resultDisplay[0]))) {

jacob314 · 2026-04-02T22:45:12Z

-        ? []
-        : data.slice(-numLinesRetained)
-    : [];
+  const arrayData = Array.isArray(data) ? data : [];


adding checks like this makes it hard for us to get this code right as you are now quietly not rendering anything with no logging or indication of what went wrong.
Can you try to root cause the issue a little rather than papering it over?

jacob314 · 2026-04-02T22:45:37Z

      'fileDiff' in contentData
    ) {
      content = (
        <DiffRenderer


this part is a nice improvement!

jacob314

Fix crash.

619fcc4

gemini-code-assist bot reviewed Apr 2, 2026

View reviewed changes

jacob314 reviewed Apr 2, 2026

View reviewed changes

gemini-cli bot added the status/need-issue Pull requests that need to have an associated issue. label Apr 2, 2026

joshualitt approved these changes Apr 2, 2026

View reviewed changes

github-actions bot mentioned this pull request Apr 3, 2026

📊 AI CLI 工具社区动态日报 2026-04-03 gsscsd/big_model_radar#125

Open

jacob314 approved these changes Apr 3, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Fix crash from unsafe typings#24578

Fix crash from unsafe typings#24578
gundermanc wants to merge 1 commit intomainfrom
resume-bug

gundermanc commented Apr 2, 2026

Uh oh!

gemini-code-assist bot commented Apr 2, 2026

Uh oh!

gemini-code-assist bot left a comment

Uh oh!

gemini-code-assist bot Apr 2, 2026

Uh oh!

gemini-code-assist bot Apr 2, 2026

Uh oh!

jacob314 Apr 2, 2026

Uh oh!

jacob314 Apr 2, 2026

Uh oh!

jacob314 left a comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

	} else if (Array.isArray(contentData)) {
	} else if (Array.isArray(contentData) && (contentData.length === 0 \|\| Array.isArray(contentData[0]))) {

		@@ -178,18 +178,13 @@ export const ToolResultDisplay: React.FC<ToolResultDisplayProps> = ({
		// Virtualized path for large ANSI arrays
		if (Array.isArray(resultDisplay)) {

	if (Array.isArray(resultDisplay)) {
	if (Array.isArray(resultDisplay) && (resultDisplay.length === 0 \|\| Array.isArray(resultDisplay[0]))) {

Conversation

gundermanc commented Apr 2, 2026

Summary

Uh oh!

gemini-code-assist bot commented Apr 2, 2026

Summary of Changes

Highlights

Footnotes

Uh oh!

gemini-code-assist bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist bot Apr 2, 2026

Choose a reason for hiding this comment

Uh oh!

gemini-code-assist bot Apr 2, 2026

Choose a reason for hiding this comment

Uh oh!

jacob314 Apr 2, 2026

Choose a reason for hiding this comment

Uh oh!

jacob314 Apr 2, 2026

Choose a reason for hiding this comment

Uh oh!

jacob314 left a comment

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants