Can't parse 'src'. Sequence item with index 0 has a wrong type (OpenCV- .train)

Question

I can't figure out why my snippet of code keeps failing, maybe some of you could help.

import re
import cv2 as cv
import os 
import numpy as np
from PIL import Image



import pickle 
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
image_dir = os.path.join(BASE_DIR, "Faces")


face_cascade = cv.CascadeClassifier(r'C:\Users\swhit\Documents\OPENCVTests\Basic-Augmented-reality-course-opencv-master\GENERATE_MARKERS\Cascades\data\haarcascade_frontalface_alt.xml')
recognizer = cv.face.LBPHFaceRecognizer_create()


current_id = 0
label_ids = {}
y_labels = []
x_train = []

for root, dirs, files in os.walk(image_dir):
    for file in files:
        if file.endswith("png") or file.endswith("jpg"):
            path = os.path.join(root, file)
            label = os.path.basename(os.path.dirname(path)).replace(" ", "-").lower()
            #print(label, path)
            if label in label_ids:
                pass
            else:
                label_ids[label] = current_id
                current_id += 1
            id_ = label_ids[label]


            y_labels.append(label) # Some number
            x_train.append(path) # Verify this, turn into NUMPY, GRAY
            pil_image = Image.open(path).convert("L") # Grayscale
            image_array = np.array(pil_image, "uint8")
            #print(image_array)
            faces = face_cascade.detectMultiScale(image_array, scaleFactor=1.5, minNeighbors=5)

            for (x,y,w,h) in faces:
                roi = image_array[y:y+h, x:x+w]
                x_train.append(roi)
                y_labels.append(id_)

#print(y_labels)
#print(x_train)

with open("labels.pickle", 'wb') as f:
    pickle.dump(label_ids, f)

recognizer.train(x_train, np.array(y_labels))
recognizer.save("trainer.yml")
            

In specific it's the recognizer.train(x_train, np.array(y_labels)) part. I get this error code

OpenCV(4.6.0) :-1: error: (-5:Bad argument) in function 'train'
> Overload resolution failed:
>  - Can't parse 'src'. Sequence item with index 0 has a wrong type
>  - Can't parse 'src'. Sequence item with index 0 has a wrong type.