Example Process

from PyQt5.QtCore import QCoreApplication, QVariant
from qgis.core import (QgsProcessingUtils,
                   QgsProcessing,
                   QgsFeatureSink,
                   QgsProject,
                   QgsLayerTreeLayer,
                   QgsFields,
                   QgsField,
                   QgsWkbTypes,
                   QgsFeature,
                   QgsGeometry,
                   QgsFeatureRequest,
                   QgsVectorLayer,
                   QgsProcessingException,
                   QgsProcessingAlgorithm,
                   QgsProcessingParameterFeatureSource,
                   QgsProcessingFeatureSourceDefinition,
                   QgsProcessingParameterField,
                   QgsProcessingParameterNumber,
                   QgsProcessingParameterPoint,
                   QgsProcessingParameterString,
                   QgsProcessingParameterEnum,
                   QgsProcessingParameterFeatureSink
                   )
import processing
import sys
from qgis.utils import iface

class crashexample(QgsProcessingAlgorithm):

    ORIG = 'ORIG'

    def createInstance(self):
        return crashexample()

    def tr(self, string):
        """
        Returns a translatable string with the self.tr() function.
        """
        return QCoreApplication.translate('Processing', string)

    def name(self):
        return 'crashexample'

    def displayName(self):
        return self.tr('Crash Example')

    def group(self):
        return self.tr('Debugging Scripts')

    def groupId(self):
        return 'debuggingscripts'

    def shortHelpString(self):
        return self.tr("<p>This script demonstrates a bug with version 3.16 (Hannover) whereby if you run this script manually it will be fine but if you run it using <b>processing.createAlgorithmDialog(\"script:crashexample\",{}).show()</b> via the python console QGIS on Windows 10 will crash. The crash will happen when you click the three dots to select the point on the map canvas. </p><p>Fault code in the Windows Event viewer should be: <br>Faulting application name: qgis-bin-g7.exe, version: 0.0.0.0, time stamp: 0x5f9304c8<br>Faulting module name: KERNELBASE.dll, version: 10.0.18362.1411, time stamp: 0xeb8644a5<br>Exception code: 0xc0000005<br>Fault offset: 0x0000000000043b29")

    def initAlgorithm(self, config=None):
        self.addParameter(QgsProcessingParameterPoint(self.ORIG, 'Origin coordinates',None,True))

    def processAlgorithm(self, parameters, context, feedback):
        originPoint = self.parameterAsPoint(parameters, self.ORIG, context)