Calling setLegendSymbolItem in processing alg cause crash

What is the bug or the crash?

When trying to update a symbol of a given layer from a Processing Script, calling the function setLegendSymbolItem on the renderer or a clone of the renderer. I always get a hard crash. When disabling this function from my processing function, everything runs fine.

Steps to reproduce the issue

Use the following script


from qgis.PyQt.QtCore import QCoreApplication
from qgis.PyQt.QtXml import QDomDocument
from qgis.core import (QgsProcessing,
                       QgsExpressionContext,QgsExpression,QgsColorUtils,QgsExpressionContextUtils,
                       QgsFeatureSink,
                       QgsProcessingException,
                       QgsProcessingAlgorithm,
                       QgsProcessingParameterVectorLayer,QgsProcessingParameterFileDestination,
                       QgsProcessingParameterExpression)
from qgis import processing

class SymbolUpdaterProcessingAlgorithm(QgsProcessingAlgorithm):

    INPUT = 'INPUT'
    COLOREXP = 'COLOREXP'
    STYLEF='STYLEF'

    def tr(self, string):
        return QCoreApplication.translate('Processing', string)

    def createInstance(self):
        return SymbolUpdaterProcessingAlgorithm()

    def displayName(self):
        return self.tr('Symbol Color Updated')

    def group(self):

        return self.tr('Symbology')

    def groupId(self):

        return 'symbology'

    def shortHelpString(self):

        return self.tr("Updates the main symbol color to the majority color")

    def initAlgorithm(self, config=None):

        self.addParameter(
            QgsProcessingParameterVectorLayer(
                self.INPUT,
                self.tr('Input layer'),
                [QgsProcessing.SourceType.TypeVectorAnyGeometry]
            )
        )

        self.addParameter(
            QgsProcessingParameterExpression(
                self.COLOREXP,
                self.tr('Color Expression'),
                parentLayerParameterName=self.INPUT,defaultValue='color_rgb( 120,120,120)'
            )
        )
        self.addParameter( QgsProcessingParameterFileDestination(self.STYLEF,self.tr('Updated style file(unused)')))

    def processAlgorithm(self, parameters, context, feedback):

        vlayer = self.parameterAsVectorLayer(
            parameters,
            self.INPUT,
            context)

        if vlayer is None:
            raise QgsProcessingException(self.invalidSourceError(parameters, self.INPUT))

        colorExp = self.parameterAsExpression(parameters,self.COLOREXP,context)
        outputFile = self.parameterAsFileOutput(parameters, self.STYLEF, context)
        baseExp = 'majority({},filter:={})'

        currentRenderer = vlayer.renderer().clone()

        lnodes = currentRenderer.legendSymbolItems()
        expConxt = QgsExpressionContext( QgsExpressionContextUtils.globalProjectLayerScopes( vlayer ) )
        for lnode in lnodes:
            lkey = lnode.ruleKey() 
            nodesymb = lnode.symbol()
            keyStrExp = currentRenderer.legendKeyToExpression(lkey,None)[0]
            feedback.pushInfo(keyStrExp)
            keyExp = QgsExpression( baseExp.format(colorExp,keyStrExp ) )
            colorExpVal = keyExp.evaluate( expConxt )
            if colorExpVal is None:
                continue
            feedback.pushInfo(colorExpVal)
            qcolr = QgsColorUtils.colorFromString(colorExpVal)
            nodesymb.setColor( qcolr )
            feedback.pushInfo(lkey)
            currentRenderer.setLegendSymbolItem(lkey,nodesymb)

        vlayer.setRenderer(currentRenderer)
        vlayer.triggerRepaint() 
        return {self.STYLEF: outputFile}

Versions

Tested in Win 10 with 3.37 & 3.35, no recent change seem to affect that area of code.

Supported QGIS version

[ ] I'm running a supported QGIS version according to the roadmap.

New profile

[ ] I tried with a new QGIS profile

Additional context

No response

qgis / QGIS

Calling setLegendSymbolItem in processing alg cause crash #58884