TypeError: Cannot read properties of undefined (reading 'length') - ZodError.errors is undefined

[andrader]

Description:
The instructor library throws a TypeError when processing Zod validation errors. The error occurs in the fromZodErrorWithoutRuntimeCheck function when it tries to access zodError.errors, but this property is undefined.

Error Stack Trace:

TypeError: Cannot read properties of undefined (reading 'length')
  at isNonEmptyArray (http://localhost:8080/node_modules/.vite/deps/@instructor-ai_instructor.js?v=8af0ca2e:10356:16)
    at fromZodErrorWithoutRuntimeCheck (http://localhost:8080/node_modules/.vite/deps/@instructor-ai_instructor.js?v=8af0ca2e:10494:7)
    at fromZodError (http://localhost:8080/node_modules/.vite/deps/@instructor-ai_instructor.js?v=8af0ca2e:10489:10)
    at m (http://localhost:8080/node_modules/.vite/deps/@instructor-ai_instructor.js?v=8af0ca2e:10630:176)
    at async LLMWrapper.generate
    at async OpenAITalentService.extractResume
    at async processFile

Environment:

• @instructor-ai/instructor: 1.7.0
• zod: 4.0.10
• Node.js: v22.17.1
• Browser: Chrome (development with Vite)

Root Cause:
The instructor library expects zodError.errors to exist, but in Zod 4.x, the property might be named differently or structured differently than what the instructor library expects.

Reproduction:

1. Use @instructor-ai/instructor@1.7.0 with zod@4.0.10
2. Call the instructor client with a Zod schema that fails validation
3. The error handling code fails when trying to process the ZodError

Expected Behavior:
The instructor library should properly handle Zod validation errors without throwing TypeError about undefined properties.

Suggested Fix:
The instructor library should check if zodError.errors exists before trying to access its length property, or adapt to the current Zod error structure.

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Immediate Workaround

npm install zod@<4.0.0