fix: MCP error -32603: Cannot read properties of undefined (reading 'toLowerCase')

[caizhiqiangzeyuan]

fix the bug 2044

Description

1.Safer Query Handling:
Since query is typed as string, we skip unnecessary safety checks and directly process it with lowerQuery = query.trim().toLowerCase()

2.Extracted Matching Logic:
Created reusable checkMatch helper that encapsulates:
Type checking (typeof text === 'string')
Normalization (trim()+toLowerCase())
Search logic (includes())

3.Performance Optimizations:
Pre-computes lowerQuery once instead of per-filter iteration
Eliminates repeated arrow function creation in array operations

4.Improved Readability:
Flattened nested conditions
Clear separation of concerns between filtering steps
More descriptive variable names

Server Details

• Server: The search_nodes function in the MCP memory server fails with a JavaScript error when attempting to search the knowledge graph. The error indicates that the search function is trying to call .toLowerCase() on an undefined value without proper input validation.
• Changes to: Map to safe lower case

Motivation and Context

bug address

How Has This Been Tested?

Yes, Cursor and Claude.

Breaking Changes

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

[domdomegg]

Instead of this fix, I'd prefer we figure out the root cause of non-strings ending up here. E.g. insufficient input validation to the tools, or knowledge graphs being corrupted for some reason - and fix that.

[domdomegg]

Hey, thanks for the contribution! This hasn't been updated for a while, so I'm closing it to help us more easily track active contributions. If you're still interested in working on this, please feel free to reopen it. Thanks again for your contribution!