Improve error messages with source lines

[seveibar]

Summary

• include original source line info when runtime errors occur
• maintain source maps in execution context
• annotate compiled code with sourceURL
• add tests for execution error source lines

Testing

• bun test tests/execution-error-line.test.tsx
• bun test tests (fails: network-dependent tests)

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https://chatgpt.com/codex/tasks/task_b_686499c3907c832eb2f9fdd7555b782b

[cursor]

Bug: Incorrect Source Line Mapping in Error Messages

The addSourceLineToError function incorrectly uses a hardcoded offset of 6 (line - 6) when mapping stack trace line numbers to original source positions via source maps. The evalCompiledJs wrapper code adds only 4 lines before the compiled code, meaning the offset should be line - 4 to correctly align the stack trace line with the compiled code block. This arbitrary and brittle offset results in incorrect source line reporting in error messages.

lib/utils/addSourceLineToError.ts#L23-L24

eval/lib/utils/addSourceLineToError.ts

Lines 23 to 24 in 52aeffe

	const consumer = await new SourceMapConsumer(sourceMaps[path])
	const pos = consumer.originalPositionFor({ line: line - 6, column: 0 })

Fix in Cursor • Fix in Web

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