How to avoid Exception TCPDF_PARSER ERROR: decodeFilterFlateDecode: invalid code ?

Dear Friends, I am using TCPDF to merge different category PDF from folders to a single one. But with some PDF's I got error as TCPDF_PARSER ERROR: decodeFilterFlateDecode: invalid code. My controller class code is

<?php

namespace App\Http\Controllers\admin;

use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use Session;
use App\Models\ApplicationModel;
use DB;
use App\Models\NotificationsModel;
use App\Models\PostModel;
use PDF;
use LynX39\LaraPdfMerger\Facades\PdfMerger;

class ApplicationsController extends Controller
{
    public function ViewApplnPDF(Request $request)
    {     

        if(Session::has('role'))
        {
                $pdfMerger = PDFMerger::init();
                $applnId = base64_decode($request->appln_id);
                $applicantData = DB::table("ksrtc_applications")->where('ksrtc_applications.id',$applnId)
                                ->select('ksrtc_applications.*','ksrtc_applications.created_at as submitted_date','ksrtc_post.*')
                                 ->join('ksrtc_post', 'ksrtc_applications.post_id', '=', 'ksrtc_post.id')
                            ->first();
                                                                 
                $education = DB::table("ksrtc_app_education")->where('app_id',$applnId)->get()->toArray();
                $workExp = DB::table("ksrtc_work_experience")->where('app_id',$applnId)->get()->toArray();
                $addlQuali = DB::table("ksrtc_addl_qualification")->where('app_id',$applnId)->get()->toArray();
                 $applicantPhoto = "applicant_photo/".$applicantData->photo;
                 $arrayP = [
                    'applicant'=> $applicantData,  
                    'education' => $education, 
                    'addlQuali' => $addlQuali, 
                    'workExp' => $workExp,
                    'applicant_photo' => $applicantPhoto                  
                                    
                ];
                $pdf = PDF::setOptions(['isHtml5ParserEnabled' => true, 'isRemoteEnabled' => true,'chroot' => public_path()])->loadView('admin/ViewApplicationPdf', $arrayP);
                            
                $pdf->save(public_path('applicant_personal_details/appln_'.$applnId.'.pdf'));
                $pdfMerger->addPDF(public_path('applicant_personal_details/appln_'.$applnId.'.pdf'));
                $pdfMerger->addPDF(public_path('applicant_photo_id/'.$applicantData->identification_document));
                               
                foreach($education as $e)
                {            
                    $pdfMerger->addPDF(public_path('educational_qualification/'.$e->edn_certificate));
                }
               
                foreach($workExp as $w)
                {            
                    $pdfMerger->addPDF(public_path('work_experience/'.$w->exp_certificate));
                }
                foreach($addlQuali as $q)
                {            
                    $pdfMerger->addPDF(public_path('additional_qualification/'.$q->addl_certificate));
                }
                  
                $pdfMerger->merge();
                
                $pdfMerger->save(public_path('applicant_view_pdf/appln_'.$applnId.'.pdf'));
                return  response()->file('applicant_view_pdf/appln_'.$applnId.'.pdf');

                return PDF::setOptions(['isHtml5ParserEnabled' => true, 'isRemoteEnabled' => true,'chroot' => public_path()])
                ->loadView('admin/ViewApplicationPdf',$arrayP)->stream('Application_PDF.pdf');
        }
        else
        {
            return view('admin/AdminLoginForm');
        }

    }
}

I need to check the files are good for merging before get that ERROR. example : in the code

 foreach($workExp as $w)
                {            
                    $pdfMerger->addPDF(public_path('work_experience/'.$w->exp_certificate));
                }

I need to check each file in code to find it's good or bad. If BAD omit that file and continue with GOOD files for merging .

Please help

Thanks Anes