Fix legacy pdfjs dynamic import

[cansu-jarvis]

Summary

• Add a shared loadLegacyPdfJs helper that resolves pdfjs-dist/legacy/build/pdf.mjs and loads it with a native dynamic file:// import.
• Use the helper for legacy PDF loading in the PDF document loader, generic File loader, and Arxiv tool.
• Add the full-file-upload UI toggle for pdfFile.legacyBuild, preserving existing upload config defaults.
• Add a unit test for the helper.

Testing

• PATH="/opt/homebrew/opt/node@20/bin:$PATH" /Users/hermes-runtime/.npm/_npx/ee7ca6831d726ff5/node_modules/.bin/pnpm --filter flowise-components test -- src/utils.test.ts --runInBand
• PATH="/opt/homebrew/opt/node@20/bin:$PATH" /Users/hermes-runtime/.npm/_npx/ee7ca6831d726ff5/node_modules/.bin/pnpm --filter flowise-components build
• PATH="/opt/homebrew/opt/node@20/bin:$PATH" ./node_modules/.bin/eslint packages/components/src/utils.ts packages/components/src/utils.test.ts packages/components/nodes/documentloaders/Pdf/Pdf.ts packages/components/nodes/documentloaders/File/File.ts packages/components/nodes/tools/Arxiv/core.ts --ext ts --report-unused-disable-directives --max-warnings 0
• PATH="/opt/homebrew/opt/node@20/bin:$PATH" node -e "const u=require('./packages/components/dist/src/utils.js'); u.loadLegacyPdfJs().then(m=>console.log(typeof m.getDocument, m.version)).catch(e=>{console.error(e); process.exit(1)})"
• PATH="/opt/homebrew/opt/node@20/bin:/Users/hermes-runtime/.npm/_npx/ee7ca6831d726ff5/node_modules/.bin:$PATH" ./node_modules/.bin/eslint packages/ui/src/ui-component/extended/FileUpload.jsx --ext js,jsx --report-unused-disable-directives --max-warnings 0
• PATH="/opt/homebrew/opt/node@20/bin:$PATH" /Users/hermes-runtime/.npm/_npx/ee7ca6831d726ff5/node_modules/.bin/pnpm --filter flowise-ui build

[gemini-code-assist]

Code Review

This pull request introduces a loadLegacyPdfJs utility function in packages/components/src/utils.ts to handle the dynamic loading of the pdfjs-dist legacy ESM build, ensuring compatibility within a CommonJS environment by bypassing TypeScript's transpilation. This utility is integrated into the File, Pdf, and Arxiv document loaders. A review comment suggests that loadLegacyPdfJs should return the entire module object rather than a subset containing only getDocument and version to maintain consistency with standard dynamic imports and prevent potential breakage for consumers expecting other module exports.

[gemini-code-assist]

The loadLegacyPdfJs function currently returns a subset of the pdfjs-dist module (getDocument and version). This might break compatibility if the consumer (e.g., PDFLoader or a user-defined script) expects other parts of the module, such as GlobalWorkerOptions or OPS. It is safer and more flexible to return the entire module object, matching the behavior of a standard dynamic import(). Per repository guidelines, using a default implementation is preferred unless specific behavior is required, and signature changes are acceptable for internal functions if callers are unaffected.

export const loadLegacyPdfJs = async (
    importer: NativeModuleImporter = nativeImport,
    resolver: ModuleResolver = (specifier) => require.resolve(specifier)
): Promise<any> => {
    const modulePath = resolver('pdfjs-dist/legacy/build/pdf.mjs')
    return await importer(pathToFileURL(modulePath).href)
}

References

1. Use a default (fallback) implementation unless the specific implementation has meaningfully different behavior or provides better error messages.
2. A signature change that would be a breaking change for a public API is acceptable for an internal function if all its callers are known and unaffected by the change.