App Service Environment deployment fails with Bad Request - Location parameter invalid

[Deploy an App Service Environment with an AppService Plan and Logic App onto an existing Virtual Network](https://github.com/Azure/azure-quickstart-templates/tree/master/app-service-environment-serviceplan-logicapp)

### Issue Details
Fails to deploy after a few seconds with error "Bad Request".

#### Status message
{
"Code": "BadRequest",
"Message": "The parameter Location has an invalid value.",
"Target": null,
"Details": [
{
"Message": "The parameter Location has an invalid value."
},
{
"Code": "BadRequest"
},
{
"ErrorEntity": {
"Code": "BadRequest",
"Message": "The parameter Location has an invalid value.",
"ExtendedCode": "51008",
"MessageTemplate": "The parameter {0} has an invalid value.",
"Parameters": [
"Location"
],
"InnerErrors": null
}
}
],
"Innererror": null
}

### Repro steps (*if necessary, delete otherwise*)
1. Create Classic VNET
2. Deploy with no changes, except VNET

Start with the linked app-service-environment-serviceplan-logicapp template and reproduce the deployment using a classic VNET, as described in the issue. Check how the deployment supplies the Location parameter and verify the template deploys successfully without the reported Bad Request.

Written by the indexing model from the issue text.