Create a resource ONLY IF that does not exist - azure

Question

I have the following bicep file to create an Azure Function App with a staging slot:
module functionAppTemplate 'functionApp.bicep' = {
name: 'functionAppTemplate'
params: {
name: '${functionAppName}'
kind: functionAppKind
location: location
servicePlanName: servicePlanName
secretSettings: union(appSettings, productionSettings)
}
dependsOn: [
servicePlanTemplate
]
}
module functionAppSlotTemplate 'functionAppSlot.bicep' = {
name: 'functionAppSlotTemplate'
params: {
name: '${functionAppName}/staging'
kind: functionAppKind
location: location
servicePlanName: servicePlanName
secretSettings: union(appSettings, stagingSettings)
}
dependsOn: [
functionAppTemplate
]
}
functionApp.bicep
resource functionApp 'Microsoft.Web/sites#2018-02-01' = {
name: name
location: location
kind: kind
properties: {
serverFarmId: resourceId('Microsoft.Web/serverfarms', servicePlanName)
clientAffinityEnabled: false
httpsOnly: true
siteConfig: {
use32BitWorkerProcess : false
appSettings: secretSettings
}
}
identity: {
type: 'SystemAssigned'
}
}
functionAppSlot.bicep
resource functionAppSlot 'Microsoft.Web/sites/slots#2018-11-01' = {
name: name
kind: kind
location: location
properties: {
clientAffinityEnabled: true
enabled: true
httpsOnly: true
serverFarmId: resourceId('Microsoft.Web/serverfarms', servicePlanName)
siteConfig: {
use32BitWorkerProcess : false
appSettings: secretSettings
}
}
identity: {
type: 'SystemAssigned'
}
}
Is there a way to run functionApp.bicep and create Function App resource ONLY IF that resource doesn't exist?