Discrepancy in lineplot responses with no data

[jernestmyers]

I've been looking into this issue re: lineplot errors with null values. I notice that at a certain zoom, the response from /standalone-map-xyrelationships/visualizations/lineplot is a 500 w/ error message Requested data stream 'single_tabular_dataset' did not contain any data. The client handles this by displaying a banner w/ the message The visualization cannot be made because the current subset is empty.

But if I zoom out, I instead get sent some unexpected values that break the client:

{
	"lineplot": {
		"data": [
			{
				"seriesX": [],
				"seriesY": [],
				"binSampleSize": [],
				"errorBars": []
			}
		],
		"config": {
			"variables": [{...},{...}],
			"viewport": {
				"xMin": "",
				"xMax": ""
			},
			"binSlider": {
				"min": null,
				"max": null,
				"step": null
			},
			"binSpec": {
				"type": "binWidth",
				"value": null
			}
		}
	}
}

My question: why does the request that returns that latter response not also result in the same 500 as the first request?