Undefined offset: 4 in laravel

Undefined offset: 4 in Laravel

when I click on submit button then other empty rows should be ignored.

Error screen shots

dashboard.blade.php form

controller.php

function commundityvendordata(Request $request){
            $collection = count(collect($request));
            // Insert data into database
            $cvendordata = new commundityvendordata;
            for ($i=0; $i < $collection; $i++) {
                $new_date = $request->new_date;

                $CCode=communitydata::where('c_code','=',$request->ccode[$i])->first();
                $cd_id = $CCode['cd_id'];
                $CName=communitydata::where('c_name','=',$request->cname[$i])->first();
                $cd_id = $CName['cd_id'];
                $CUnit=units::where('unit','=',$request->cunit[$i])->first();
                $unit_id = $CUnit['unit_id'];

            $vender1 = $request->vendor1[$i];
            $vender2 = $request->vendor2[$i];
            $vender3 = $request->vendor3[$i];
            $vender4 = $request->vendor4[$i];
                $commdata = [
                        'new_date'  => Carbon::parse($new_date)->format('Y-m-d'),
                        'cd_id'     => $cd_id,
                        'cn_id'     => $cd_id,
                        'unit_id'   => $unit_id,
                        'vender1'   => $vender1,
                        'vender2'   => $vender2,
                        'vender3'   => $vender3,
                        'vender4'   => $vender4
                    ];
 DB::table('commundityvendordata')->insert($commdata);
            }
            return back()->with('success','Data Saved...');
    }

via Chebli Mohamed