Broken autocomplete inside Inline after clicking "Add another ..."

[Michał Pokusa]

This error occurs on versions from 3.2 (or even before, untested) up to latest (5.2 at this time). It seems like it is only JS/CSS related.
Happens with both TabularInline and StackedInline.

Possibly related to #36336.

Tested on Google Chrome, Firefox, Edge and on mobile device.

Steps to reproduce (code below):

1. Go to change form view (editing existing object, adding new one, doesn't matter)
2. Click "X" on any inline except last one
3. Click "Add another ..." once again

Code:

models.py

from django.db import models


class Restaurant(models.Model):
    name = models.CharField(max_length=100)
    address = models.CharField(max_length=255)

    def __str__(self):
        return self.name


class Order(models.Model):
    restaurant = models.ForeignKey(Restaurant, on_delete=models.CASCADE)
    order_number = models.CharField(max_length=20)
    products = models.ManyToManyField("Product", related_name="orders")

    def __str__(self):
        return f"Order {self.pk} from {self.restaurant.name}"


class Product(models.Model):
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)

    def __str__(self):
        return f"{self.name} - ${self.price}"

admin.py

from django.contrib import admin

from .models import Restaurant, Order, Product


class OrderInline(admin.StackedInline):
    model = Order
    extra = 3

    fields = ["order_number", "products"]
    autocomplete_fields = ["products"]


@admin.register(Restaurant)
class RestaurantAdmin(admin.ModelAdmin):
    list_display = ("name", "address")
    search_fields = ("name", "address")

    inlines = [OrderInline]


@admin.register(Order)
class OrderAdmin(admin.ModelAdmin):
    list_display = ("restaurant", "order_number")


@admin.register(Product)
class ProductAdmin(admin.ModelAdmin):
    list_display = ("name", "price")

    search_fields = ("name",)

[Natalia Bidart]

Thank you Michał Pokusa, I was able to reproduce this issue with the provided steps.