Getting mimes validation fail when not uploading optional file with AJAX

Hi, I'm trying to make a bug report system where the user sends a body of text and OPTIONALLY he can upload a file (image, doc...) along with the text to be sent to my mail inbox.

However, when I only send text I get this error:

"The file must be a file of type: doc, pdf, docx, zip, odt, jpeg, bmp, png, jpg, svg."

how can I fix this, also when I upload a file along with text the mail is sent all right but the attached file is only 1kb, always.

Jquery code:

var formData = new FormData();
        formData.append('body', $('#bug_body').val());
        formData.append('file', $('#bug_file').prop('files')[0]);
        
        
        $.ajaxSetup({
            
            headers: {'X-CSRF-TOKEN': $('meta[name="csrf_token"]').attr('content')}
        
        });
        
        $.ajax({
            
            async: true,
            url: '/contactar-mail-bug',
            type: 'POST',
            data: formData,
            contentType: false,
            processData: false, 
            dataType: 'JSON',
            
            success: function (data) { 
                $('.form_valid_container').fadeIn().html('<span class="form_valid_text">✓ '+ data.success +'</span>');
                form.trigger("reset");
                console.log(data.success);
            },
            
            error: function (data){
                var errors = data.responseJSON;
                console.log(errors);
                
                $.each(errors , function(){
                    $('.form_error_container').fadeIn().html('<span class="form_error_text">✘ '+ errors.message +'</span>')
                }); 
            }

        });

Method for sending email:

public function contactar_reportar_bug(BugReport $request)
    {
        $sender_mail = config('globals.admin_mail');//mail sender, in this case it's me
        
        $destination_mail = config('globals.admin_mail');//mail receiver, in this case it's me too
        
        $client_phone = config('globals.client_phone');
        
        $body = $request->body;//bug report mail message
        
        $file = $request->file('file');//bug report screencap or doc
        
        $file_name = $file->getClientOriginalName();//outputs Laravel DOC.odt
        
        $mime_type = $file->getMimeType();//outputs application/
        
        $file_extension = $file->guessExtension();//outputs .odt
        
        $restaurant = Globals::where('name' , 'Nombre del restaurante')->pluck('value');//outputs web_name, used in the mail subject
        
        $subject = "Nuevo reporte de bug en $restaurant";//subject of the mail
        
        
        
        
        $bug = new Bug();
        $bug->body = $request->body;
        $bug->save();
        
        
        
        Mail::to($destination_mail)->send(new BugReportMail($body, $file, $subject, $restaurant, $client_phone, $sender_mail, $file_name, $mime_type));
        
        return response()->json([
        
            'success' => 'Reporte de bug enviado',
            'bug' => $bug,

        ]);
    }

Bug Report form request (notice how only the body of the message is required):

public function rules()
    {
        return [
            
            'body' => 'required|string|min:5',
            
            'file' => 'mimes:doc,pdf,docx,zip,odt,jpeg,bmp,png,jpg,svg|max:2000'
        ];
    }