Query diagnostics tend to "stick" regardless of toggle switching, so we might either continue to display a diagnostic when it's no longer valid, or we might not show diagnostics when we should.

To reproduce:

• This query shows an error diagnostic for type:commit when structural search is enabled https://sourcegraph.com/search?q=context:global+repo:%5Egithub%5C.com/sourcegraph/sourcegraph%24+type:commit+asdf&patternType=structural

• Now click the structural search toggle to disable.

• The diagnostic still shows (but it should disappear)

The other way around:

• This query shows no diagnostics, and type:commit is set: https://sourcegraph.com/search?q=context:global+repo:%5Egithub%5C.com/sourcegraph/sourcegraph%24+type:commit+asdf&patternType=structural

• Now click the structural search toggle to disable.

• No diagnostic shows up (but we should be showing the diagnostic that type:commit isn't supported)