🐛 fix(model-runtime): handle null content in anthropic message builder by arvinxx · Pull Request #11756 · lobehub/lobehub

arvinxx · 2026-01-23T15:42:32Z

Summary

Fix TypeError: Cannot read properties of null (reading 'map') when building Anthropic messages
Handle assistant messages with tool_calls but null content
Handle tool messages with null or empty string content
Use <empty_content> placeholder for null/empty content

Problem

When using MCP tools (e.g., Apollo-MCP), some responses may have:

Assistant messages: tool_calls array is non-empty but content is null
Tool messages: content is null or empty string ""

This caused two errors:

TypeError: Cannot read properties of null (reading 'map') at buildArrayContent
messages.X.content.0.tool_result.content.0.text.text: Input should be a valid string

Solution

Fix 1: Assistant message handling (anthropic.ts:117-121)

const rawContent =
  typeof content === 'string'
    ? ([{ text: message.content, type: 'text' }] as UserMessageContentPart[])
    : Array.isArray(content)
      ? content
      : ([{ text: '<empty_content>', type: 'text' }] as UserMessageContentPart[]);

Fix 2: Tool message handling (anthropic.ts:186)

const toolContent = !message.content ? '<empty_content>' : message.content;

Test plan

Added test: should handle assistant message with tool_calls but null content
Added test: should handle tool message with null content
Added test: should handle tool message with empty string content
All 29 tests pass

Related Issues

Closes: LOBE-4201, LOBE-2715

🤖 Generated with Claude Code

Fix TypeError when building Anthropic messages with null content: - Handle assistant messages with tool_calls but null content - Handle tool messages with null or empty string content - Use '<empty_content>' placeholder for null/empty content Add 3 test cases covering the null content scenarios. Closes: LOBE-4201, LOBE-2715 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

vercel · 2026-01-23T15:42:38Z

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Project	Deployment	Review	Updated (UTC)
lobehub	Canceled		Jan 24, 2026 1:28am

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gru-agent · 2026-01-23T15:42:45Z

TestGru Assignment

Summary

Link	CommitId	Status	Reason
Detail	`62bc803`	✅ Finished

History Assignment

Files

File	Pull Request
packages/model-runtime/src/core/contextBuilders/anthropic.ts	❌ Failed (I failed to setup the environment.)

Tip

You can @gru-agent and leave your feedback. TestGru will make adjustments based on your input

Tool messages may have array content, not just string. Use buildArrayContent to properly process array content in tool results. Add test case for tool message with array content. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

…ages When assistant message has tool_calls but null/empty content, filter out the empty text block instead of using placeholder. Only tool_use blocks remain in the content array. Add test case for empty string content scenario. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add test case to verify tool message with array content containing both text and image is correctly processed. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

…pty content Add test cases for tool messages without corresponding assistant tool_call when content is null or empty string. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

codecov · 2026-01-23T16:07:49Z

Codecov Report

❌ Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.16%. Comparing base (5d115ef) to head (da01632).
⚠️ Report is 13 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next   #11756      +/-   ##
==========================================
- Coverage   74.16%   74.16%   -0.01%     
==========================================
  Files        1193     1193              
  Lines       95004    95014      +10     
  Branches    12534    10499    -2035     
==========================================
+ Hits        70464    70469       +5     
- Misses      24450    24455       +5     
  Partials       90       90

Flag	Coverage Δ
app	`67.22% <ø> (ø)`
database	`91.48% <ø> (ø)`
packages/agent-runtime	`90.20% <ø> (ø)`
packages/context-engine	`85.33% <ø> (ø)`
packages/conversation-flow	`92.28% <ø> (ø)`
packages/file-loaders	`87.04% <ø> (ø)`
packages/memory-user-memory	`69.30% <ø> (ø)`
packages/model-bank	`100.00% <ø> (ø)`
packages/model-runtime	`86.69% <86.66%> (-0.03%)`	⬇️
packages/prompts	`79.33% <ø> (ø)`
packages/python-interpreter	`92.90% <ø> (ø)`
packages/ssrf-safe-fetch	`0.00% <ø> (ø)`
packages/utils	`93.22% <ø> (ø)`
packages/web-crawler	`95.62% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Store	`67.98% <ø> (ø)`
Services	`50.73% <ø> (ø)`
Server	`67.71% <ø> (ø)`
Libs	`40.36% <ø> (ø)`
Utils	`93.60% <ø> (ø)`

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lobehubbot · 2026-01-23T18:00:40Z

❤️ Great PR @arvinxx ❤️

The growth of project is inseparable from user feedback and contribution, thanks for your contribution! If you are interesting with the lobehub developer community, please join our discord and then dm @arvinxx or @canisminor1990. They will invite you to our private developer channel. We are talking about the lobe-chat development or sharing ai newsletter around the world.

## [Version 2.0.0-next.357](v2.0.0-next.356...v2.0.0-next.357) <sup>Released on **2026-01-23**</sup> #### 🐛 Bug Fixes - **model-runtime**: Handle null content in anthropic message builder. - **misc**: Page content switch mismatch. <br/> <details> <summary><kbd>Improvements and Fixes</kbd></summary> #### What's fixed * **model-runtime**: Handle null content in anthropic message builder, closes [#11756](#11756) ([539753a](539753a)) * **misc**: Page content switch mismatch, closes [#11758](#11758) ([fdc8f95](fdc8f95)) </details> <div align="right"> [![](https://img.shields.io/badge/-BACK_TO_TOP-151515?style=flat-square)](#readme-top) </div>

## [Version 1.154.0](v1.153.1...v1.154.0) <sup>Released on **2026-01-23**</sup> #### ♻ Code Refactoring - **misc**: Migrate AI Rules to Claude Code Skills. #### ✨ Features - **database**: Extended async task with metadata and parent id, added index. - **misc**: Remove NextAuth. #### 🐛 Bug Fixes - **copilot**: History popover not refreshing when agentId changes. - **editor**: Prevent crash when toggling enableInputMarkdown setting. - **home**: Use correct CreateGroupModal for session group creation. - **model-runtime**: Handle null content in anthropic message builder. - **ModelSelect**: Resolve tooltip hover causing popup to close. - **pdf**: Ensure worker config before Document render. - **store**: Delete message before regeneration. - **misc**: Fix auto scroll, fix favorite refresh bug and group topic refresh issue, fixed the agent group builder tools excaution edge case crash, page content switch mismatch, when use market group, the group sys role was not used. <br/> <details> <summary><kbd>Improvements and Fixes</kbd></summary> #### Code refactoring * **misc**: Migrate AI Rules to Claude Code Skills, closes [lobehub#11737](https://github.com/jaworldwideorg/OneJA-Bot/issues/11737) ([346fc46](346fc46)) #### What's improved * **database**: Extended async task with metadata and parent id, added index, closes [lobehub#11712](https://github.com/jaworldwideorg/OneJA-Bot/issues/11712) ([31d2f26](31d2f26)) * **misc**: Remove NextAuth, closes [lobehub#11732](https://github.com/jaworldwideorg/OneJA-Bot/issues/11732) ([1eff864](1eff864)) #### What's fixed * **copilot**: History popover not refreshing when agentId changes, closes [lobehub#11731](https://github.com/jaworldwideorg/OneJA-Bot/issues/11731) ([64f39e7](64f39e7)) * **editor**: Prevent crash when toggling enableInputMarkdown setting, closes [lobehub#11755](https://github.com/jaworldwideorg/OneJA-Bot/issues/11755) ([ea5eed8](ea5eed8)) * **home**: Use correct CreateGroupModal for session group creation, closes [lobehub#11752](https://github.com/jaworldwideorg/OneJA-Bot/issues/11752) ([36bcc50](36bcc50)) * **model-runtime**: Handle null content in anthropic message builder, closes [lobehub#11756](https://github.com/jaworldwideorg/OneJA-Bot/issues/11756) ([539753a](539753a)) * **ModelSelect**: Resolve tooltip hover causing popup to close, closes [lobehub#11742](https://github.com/jaworldwideorg/OneJA-Bot/issues/11742) ([1b73f14](1b73f14)) * **pdf**: Ensure worker config before Document render, closes [lobehub#11746](https://github.com/jaworldwideorg/OneJA-Bot/issues/11746) ([ad34072](ad34072)) * **store**: Delete message before regeneration, closes [lobehub#11760](https://github.com/jaworldwideorg/OneJA-Bot/issues/11760) ([a8a6300](a8a6300)) * **misc**: Fix auto scroll, closes [lobehub#11734](https://github.com/jaworldwideorg/OneJA-Bot/issues/11734) ([892fa9f](892fa9f)) * **misc**: Fix favorite refresh bug and group topic refresh issue, closes [lobehub#11745](https://github.com/jaworldwideorg/OneJA-Bot/issues/11745) ([5d115ef](5d115ef)) * **misc**: Fixed the agent group builder tools excaution edge case crash, closes [lobehub#11735](https://github.com/jaworldwideorg/OneJA-Bot/issues/11735) ([5de4742](5de4742)) * **misc**: Page content switch mismatch, closes [lobehub#11758](https://github.com/jaworldwideorg/OneJA-Bot/issues/11758) ([fdc8f95](fdc8f95)) * **misc**: When use market group, the group sys role was not used, closes [lobehub#11739](https://github.com/jaworldwideorg/OneJA-Bot/issues/11739) ([afc76f9](afc76f9)) </details> <div align="right"> [![](https://img.shields.io/badge/-BACK_TO_TOP-151515?style=flat-square)](#readme-top) </div>

sourcery-ai bot reviewed Jan 23, 2026

View reviewed changes

dosubot bot added the size:L This PR changes 100-499 lines, ignoring generated files. label Jan 23, 2026

dosubot bot added the 🐛 Bug label Jan 23, 2026

arvinxx and others added 3 commits January 23, 2026 23:44

arvinxx force-pushed the fix/anthropic-null-content branch from 504a5b5 to 36a13d7 Compare January 23, 2026 15:55

arvinxx merged commit 539753a into next Jan 23, 2026
40 of 43 checks passed

arvinxx deleted the fix/anthropic-null-content branch January 23, 2026 17:57

vercel bot deployed to Preview January 24, 2026 01:28 View deployment

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🐛 fix(model-runtime): handle null content in anthropic message builder#11756

🐛 fix(model-runtime): handle null content in anthropic message builder#11756
arvinxx merged 5 commits intonextfrom
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arvinxx commented Jan 23, 2026

Summary

Problem

Solution

Fix 1: Assistant message handling (anthropic.ts:117-121)

Fix 2: Tool message handling (anthropic.ts:186)

Test plan

Related Issues

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