fix(langchain): Fix structured parser error handling #7232
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| text | ||
| ); | ||
| // eslint-disable-next-line no-instanceof/no-instanceof | ||
| if (e instanceof SyntaxError && e.message.includes("JSON")) { |
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Can't use instanceof as it's not available in all JS environments.
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It's not that it doesn't exist, it's just that it's not always reliable for packages since in some environments bundlers can duplicate class definitions across multiple chunks
(native classes I think are ok)
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Do you think it would be better to change this condition to something like if (e && (e as Error).name !== "ZodError")?
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Unfortunately minifiers can also mess with that 😬
It looks like SyntaxError is a native object though?
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SyntaxError
So probably ok to do the instanceof check
| return await this.schema.parseAsync(JSON.parse(text.trim())); | ||
| } catch (e2) { | ||
| throw new OutputParserException( | ||
| `Failed to parse. Text: "${text}". Error: ${e2}`, |
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If e2 is an object, it will not be rendered properly in this message. Please add a check beforehand which stringifies the error if it's an object
This was an issue before, but we should fix now.
Previously, StructuredOutputParser would sometimes throw JSON.parse errors instead of the original Zod schema validation errors.
This PR modifies the fallback mechanism to only trigger for JSON parsing failures, while preserving Zod's schema validation errors.
Relevant links: