Query Builder crashes when query is pasted in under certain circumstances

Customer is reporting an issue with the query builder: https://github.com/influxdata/feature-requests/issues/523

> When a query is pasted in with a colon (":") instead of an equal sign ("=") in a function definition for a variable default the page crashes.
>
> "The old editor hangs then crashes the Chrome page.
>
> The new editor seems to survive, but pressing the spacebar causes it to crash too.
>
> The API returns 502 after a long time."
>
> In the past this type of error did not crash the page when it was made previously.