I don't have any variables set, and when running a mutation; I get the following error:
```
Error SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)
at VueComponent._callee$ (graphql.vue?f047:505)
at tryCatch (runtime.js?96cf:45)
at Generator.invoke [as _invoke] (runtime.js?96cf:271)
at Generator.prototype.<computed> [as next] (runtime.js?96cf:97)
at asyncGeneratorStep (asyncToGenerator.js?1da1:3)
at _next (asyncToGenerator.js?1da1:25)
at eval (asyncToGenerator.js?1da1:32)
at new Promise (<anonymous>)
at VueComponent.eval (asyncToGenerator.js?1da1:21)
```
Setting the `variablesJSONString` variable to the correct default (`{}`) fixes this issue :)
