{
  "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "existingLabName": {
      "value": "MyLab1"
    },
    "existingVMResourceId": {
      "value": "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/MyLabRG/providers/Microsoft.DevTestLab/environments/MyVM1"
    },
    "newTemplateName": {
      "value": "MyVMTemplate1"
    },
    "newTemplateDescription": {
      "value": "Some description for the VM template"
    }
  }
}

{
  "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "existingLabName": {
      "value": "MyLab1"
    },
    "existingVMResourceId": {
      "value": "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/MyLabRG/providers/Microsoft.DevTestLab/environments/MyVM1"
    },
    "TemplateName": {
      "value": "MyVMTemplate1"
    },
    "TemplateDescription": {
      "value": "Some description for the VM template"
    }
  }
}

Fix for bug detected by @acomghbot
Fix for bug detected by @acomghbot
