Notebook query preview exists even before the data source is selected

[nemanjaglumac]

Describe the bug

We're showing the notebook query preview even before someone selects a data source. Clicking on it will result in a forever loading spinner and a failed POST /api/dataset request.

To Reproduce

1. Click on "New" > Question
   
2. Click on the little preview button next to the blue "Pick your starting data" rectangle
3. The loader is spinning ad infinitum and there is a failed request in the network tab
   

Expected behavior

The preview button should appear only when a query can run, i.e. when there is a data source.

Logs

{
  "via": [
    {
      "type": "clojure.lang.ExceptionInfo",
      "message": "`database` is required for all queries whose type is not `internal`.",
      "data": {
        "status-code": 400,
        "query": {
          "type": "query",
          "query": {
            "limit": 10
          },
          "parameters": [],
          "middleware": {
            "js-int-to-string?": true,
            "userland-query?": true,
            "add-default-userland-constraints?": true
          },
          "info": null
        }
      },
      "at": [
        "metabase.api.dataset$fn__114124$_AMPERSAND_f__114127",
        "doInvoke",
        "dataset.clj",
        60
      ]
    }
  ],
  "trace": [
    [
      "metabase.api.dataset$fn__114124$_AMPERSAND_f__114127",
      "doInvoke",
      "dataset.clj",
      60
    ],
    [...],
    [
      "java.lang.Thread",
      "run",
      "Thread.java",
      829
    ]
  ],
  "cause": "`database` is required for all queries whose type is not `internal`.",
  "data": {
    "status-code": 400,
    "query": {
      "type": "query",
      "query": {
        "limit": 10
      },
      "parameters": [],
      "middleware": {
        "js-int-to-string?": true,
        "userland-query?": true,
        "add-default-userland-constraints?": true
      },
      "info": null
    }
  },
  "message": "`database` is required for all queries whose type is not `internal`.",
  "query": {
    "type": "query",
    "query": {
      "limit": 10
    },
    "parameters": [],
    "middleware": {
      "js-int-to-string?": true,
      "userland-query?": true,
      "add-default-userland-constraints?": true
    },
    "info": null
  }
}

Information about your Metabase installation

local dev, master, dc279fd, H2, Sample Database

Severity

P3