* Return empty list of tags when tags are not available
In some configurations graphite-web fail to return the list of tags. It shouldn't however prevent displaying list of metrics (which is concatenated with tags).
* Populate jsonData with default version of Graphite
The version of Graphite is preselected in the dropdown but was not saved in jsonData initially.
* Fix a typo
* Show a popup with an error message
* Always use the latest Graphite value as the default one when creating a datasource
* Move autocomplete error handling to GraphiteQueryCtrl
* Test error handing in Graphite autocomplete
* Test default Graphite version fallback
* Rename graphite_versions.ts to versions.ts
* Remove redundant import
* Code formatting, minor renaming
* Remove redundant error info
