fix: stream files too large to read unbuffered

[vibhor-aggr]

Closes #103.

When fs.readFileSync() reports ERR_FS_FILE_TOO_LARGE, unbuffered mode should still be able to serve the file through the existing stream path instead of crashing while trying to compute the eager MD5.

This preserves the current eager hash behavior for ordinary files, rethrows other read failures, and still rethrows the too-large error when options.buffer is enabled because that mode requires the file in memory.

Verification:

• ./node_modules/.bin/mocha --grep 'unbuffered read is too large'
• npm test
• git diff --check

Summary by Sourcery

Handle large files in unbuffered mode without crashing by falling back to streaming when eager reads exceed size limits.

Bug Fixes:

• Avoid crashes when fs.readFileSync throws ERR_FS_FILE_TOO_LARGE in unbuffered, dynamic mode by skipping eager buffering and MD5 computation.

Tests:

• Add a regression test to ensure dynamic unbuffered responses stream correctly when readFileSync reports files as too large.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: bfbfdefe-8cb3-415c-9571-9ffdaaf8d840

📥 Commits

Reviewing files that changed from the base of the PR and between 182f260 and b1438ac.

📒 Files selected for processing (2)

• index.js
• test/index.js

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Reviewer's Guide

Handles ERR_FS_FILE_TOO_LARGE when loading static files so unbuffered, dynamic mode falls back to streaming instead of crashing, and adds a regression test for this behavior.

File-Level Changes

Change	Details	Files
Handle ERR_FS_FILE_TOO_LARGE when eagerly reading files so unbuffered dynamic mode can still stream large files while buffered mode continues to require fully reading the file.	Wrap fs.readFileSync in a try/catch when loading files to intercept read errors Suppress ERR_FS_FILE_TOO_LARGE only when options.buffer is false, otherwise rethrow the error Skip MD5 hash computation when the file buffer is unavailable, preserving existing behavior for successfully read files	index.js
Add regression test to simulate too-large unbuffered reads and assert that files are still streamed successfully in dynamic mode.	Introduce mz/fs and os dependencies in the test suite for mocking readFileSync and creating temporary directories Add a test case that creates a temporary large file, monkey-patches mzfs.readFileSync to throw ERR_FS_FILE_TOO_LARGE for that file, and verifies a 200 response with the expected body Ensure cleanup restores the original readFileSync and removes temporary files and directories	test/index.js

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#103	Prevent the application from crashing with RangeError[ERR_FS_FILE_TOO_LARGE] when serving files larger than 2GB in unbuffered mode (buffer: false), and allow those files to be streamed instead.	✅
#103	Preserve existing behavior for other read errors and when buffer: true (i.e., still throw on ERR_FS_FILE_TOO_LARGE when buffering is required).	✅

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