Broken `vis` in an example breaks extension

[travisby]

Hello!

I had a syntax error in my explore example. In particular, the output ended in &vis={"type":"looker_bar". NOTE the missing closing brace.

This led to the explore assistant UI throwing a console error:

bundle.js:75 vis={"type":"looker_bar"
08:37:06.020 VM52095:1 Uncaught (in promise) SyntaxError: Expected ',' or '}' after property value in JSON at position 20 (line 1 column 21)
    at JSON.parse (<anonymous>)
    at bundle.js:75:98060
    at bundle.js:75:98300
    at Array.map (<anonymous>)
    at bundle.js:75:97280
    at bundle.js:75:150651
    at Generator.next (<anonymous>)
    at e (bundle.js:2:1402454)
    at s (bundle.js:2:1402657)
    at bundle.js:2:1402716

And the application hung, appearing as if it was still waiting for a response from Vertex.

This looks like this LOC:

looker-explore-assistant/explore-assistant-extension/src/utils/ExploreHelper.ts

Line 28 in fe07fe0

const visString = vis_config ? JSON.stringify(vis_config) : ''

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This happens even if the question I'm asking is unrelated to that example (but related to that explore!)

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It'd be great if the extension did some validation or spit out louder when an error occurred. It took me a while to realize there was a console error, after hours of network request and model debugging 😆