'PyQt5.QtCore.pyqtSignal' object has no attribute 'emit'

Question

I wrote a SnippingWidget function and linked it to the main code. After executing this function, my application crashes with an error. I looked up what the error is with try and it says: "PyQt5.QtCore.pyqtSignal' object has no attribute 'emit'". I want this function to just hide itself when finished, meaning it can be reused. Initially the same error came up, but with "closed", I was able to solve it. But I don't understand what to do with emit....

Here is the code for my function:

from PyQt5 import QtCore, QtGui, QtWidgets
 
class SnippingWidget(QtWidgets.QDialog):
    closed = QtCore.pyqtSignal()

    def __init__(self):
        super(SnippingWidget, self).__init__()
        self.setAttribute(QtCore.Qt.WA_NoSystemBackground, True)
        self.setAttribute(QtCore.Qt.WA_TranslucentBackground, True)
        self.setStyleSheet("background:transparent;")
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)
 
        self.outsideSquareColor = "red"
        self.squareThickness = 2
 
        self.start_point = QtCore.QPoint()
        self.end_point = QtCore.QPoint()
        self.selected_area = None
 
        # Установка размеров окна в соответствии с размерами экрана
        screen_geometry = QtWidgets.QApplication.desktop().screenGeometry()
        self.setGeometry(screen_geometry)
 
    def mousePressEvent(self, event):
        self.start_point = event.pos()
        self.end_point = event.pos()
        QtWidgets.QApplication.setOverrideCursor(QtCore.Qt.CrossCursor)
        self.update()
 
 
    def mouseMoveEvent(self, event):
        self.end_point = event.pos()
        self.update()
 
    def mouseReleaseEvent(self, QMouseEvent):
        r = QtCore.QRect(self.start_point, self.end_point).normalized()
        self.hide()
        self.selected_area = r
        QtWidgets.QApplication.restoreOverrideCursor()
        self.closed.emit()
        self.start_point = QtCore.QPoint()
        self.end_point = QtCore.QPoint()
 
    def paintEvent(self, event):
        trans = QtGui.QColor(22, 100, 233)
        r = QtCore.QRectF(self.start_point, self.end_point).normalized()
        qp = QtGui.QPainter(self)
        trans.setAlphaF(0.2)
        qp.setBrush(trans)
        outer = QtGui.QPainterPath()
        outer.addRect(QtCore.QRectF(self.rect()))
        inner = QtGui.QPainterPath()
        inner.addRect(r)
        r_path = outer - inner
        qp.drawPath(r_path)
        qp.setPen(
            QtGui.QPen(QtGui.QColor(self.outsideSquareColor), self.squareThickness)
        )
        trans.setAlphaF(0)
        qp.setBrush(trans)
        qp.drawRect(r)

For "closed", I defined a closed signal:

closed = QtCore.pyqtSignal()