fix(gatsby): add sanity check before displaying path for static html build error

[pieh]

We currently swallow errors and display Cannot read property 'path' of undefined if error wasn't decorating with context[.path]. This can happen if error is thrown just when requiring render-page module (in

gatsby/packages/gatsby/src/utils/worker.js

Line 25 in 2032147

const htmlComponentRenderer = require(htmlComponentRendererPath)

)

It doesn't make sense to add path for page for those errors because it's not page specific and would throw for all pages, so instead let's add sanity check before trying to output path for page.

The bug can be reproduced by cloning https://github.com/dfds-frontend/gatsby-dfds-starter/tree/5f2568ebe3c79bfbc093a3d1fd7d78ae6da8f93e and commenting out en var sanity check in gatsby-config.js

[DSchau]

✅

[KyleAMathews]

Nice!