Image not resizing as it is not being loaded, where am I going wrong (opencv)

Question

I am using this code to split a folder of 3000 images into seperate directories to use in a classifier.

the error is

'OpenCV(4.0.1) C:\ci\opencv-suite_1573470242804\work\modules\imgproc\src\resize.cpp:3784: error: (-215:Assertion failed) !ssize.empty() in function 'cv::resize'

Telling me the image variable is empty? I have checked the path it seems ok.. but am I missing something? More of a code check.

## build a cats v dogs image dataset

from os import listdir
from os.path import isfile, join
import cv2
import numpy as np
import sys
import os 
import shutil

mypath = r"data\catsdogs\images"

file_names = [f for f in listdir(mypath) if isfile(join(mypath,f))]

print(str(len(file_names))+' images loaded')

#extract 1000 images for training and 500 for validation

dog_count = 0
cat_count = 0
training_size = 1000
test_size = 500
training_images=[]
training_labels =[]
test_images = []
test_labels = []
size = 150

dog_dir_train = r"data\catsdogs\train\dogs"
cat_dir_train = r"data\catsdogs\train\cats"
dog_dir_val =  r"data\catsdogs\validation\dogs"
cat_dir_val =  r"data\catsdogs\validation\cats"

def make_dir(directory):
    if os.path.exists(directory):
        shutil.rmtree(directory)
    os.makedirs(directory)
    
make_dir(dog_dir_train)
make_dir(cat_dir_train)
make_dir(dog_dir_val)
make_dir(cat_dir_val)

def getZeros(number):
    if (number >10 and number <100):
        return "0"
    if (number <10):
        return "00"
    else:
        return ""
    
for i, file in enumerate(file_names):
    
    if file_names[i][0] == 'd':
        dog_count +=1
        image=cv2.imread(mypath+file)
        image=cv2.resize(image,(size,size), interpolation = cv2.INTER_AREA)
        if dog_count <= training_size:
            training_images.append(image)
            training_labels.append(1)
            zeros = getZeros(dog_count)
            cv2.imwrite(dog_dir_train +'dog' +str(zeros)+str(dog_count)+'.jpg',image)
        if dog_count> training_size and dog_count <=training_size+test_size:
            test_images.append(image)
            test_labels.append(1)
            zeros = getZeros(dog_count-1000)
            cv2.imwrite(dog_dir_val + 'dog' + str(zeros)+str(dog_count-1000) + '.jpg', image)
            
    if file_names[i][0] == 'c':
        cat_count +=1
        image=cv2.imread(mypath+file)
        image=cv2.resize(image,(size,size), interpolation = cv2.INTER_AREA)
        if cat_count <= training_size:
            training_images.append(image)
            training_labels.append(1)
            zeros = getZeros(cat_count)
            cv2.imwrite(cat_dir_train +'cat' +str(zeros)+str(cat_count)+'.jpg',image)
        if cat_count> training_size and cat_count <=training_size+test_size:
            test_images.append(image)
            test_labels.append(1)
            zeros = getZeros(cat_count-1000)
            cv2.imwrite(cat_dir_val + 'cat' + str(zeros)+str(cat_count-1000) + '.jpg', image)
            
            
            
        if dog_count == training_size+test_size and cat_count == training_size+test_size:
            break
        
print ('training and test data extraction complete')
            
            

I also am using 'r' before some paths. Is the best way as without it the code could not function.