Silent error on parse semi-transparent content

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
28/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript
Domain
backend

Research direction

Reproduce the failure with Declaration.pdf or the pdf2json.js command shown in the issue, then inspect /base/core/jpg.js around lines 832-833 and the pdfParser_dataError handling path. Verify how four-component JPEGs are handled and ensure parsing reports a useful error or completes without silently stopping; retest the reported document and the existing sample command.

Written by the indexing model from the issue text.

Description

Hello, recently I found bug with parsing some .pdf files. If file have symbols colored in semi-transparent color, a program just stops without any error messages. Here's code which stops silent (declaration.pdf - "unparsable" document):

let fs = require('fs'),
    PDFParser = require("pdf2json");

let pdfParser = new PDFParser(this, 1);

pdfParser.on("pdfParser_dataError", errData => console.error(errData.parserError) );
pdfParser.on("pdfParser_dataReady", pdfData => {
    fs.writeFile("./content.txt", pdfParser.getRawTextContent());
});

pdfParser.loadPDF("./Declaration.pdf");

So, after I tried to parse document directly with pdf2json:
node pdf2json.js "../../documents/whitepaper/47/WP_En.pdf" "../../"
And I got some errors:

Warning: Unhandled rejection: Error: JPEG error: Unsupported color mode (4 components)
Error: JPEG error: Unsupported color mode (4 components)
    at error (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:195:9)
    at JpegStream_ensureBuffer [as ensureBuffer] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:25571:7)
    at JpegStream.DecodeStream_getBytes [as getBytes] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:24875:14)
    at PDFImage_getImageBytes [as getImageBytes] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:21009:25)
    at PDFImage_fillRgbaBuffer [as fillRgbaBuffer] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:20941:27)
    at PDFImage_getImageData [as getImageData] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:21004:12)
    at eval (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:7125:34)
    at Object.eval [as onResolve] (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:20657:7)
    at Object.runHandlers (eval at <anonymous> (app\node_modules\pdf2json\lib\pdf.js:64:1), <anonymous>:864:35)
    at ontimeout (timers.js:466:11)

In a nutshell, my solution was to comment 2 lines(832-833) in /base/core/jpg.js:

if (!this.adobe)
    throw 'Unsupported color mode (4 components)';

After that I successfully parsed my document.

So, @modesty, can you fix this or just remove?

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