Add test to make sure the archive doesn't fail when event for event relation is missing and not included in list of provided events. Like if someone is replying to an event that was from long ago out of our range.
In the case of missing relations, Hydrogen does `_loadContextEntryNotInTimeline` because it can't find the event locally which throws an `uncaughtException`. Before https://github.com/matrix-org/matrix-public-archive/pull/51, the `uncaughtException` killed the Hydrogen `child_process` before it could pass back the HTML. Now this PR mainly just adds a test to make sure it works.
```
TypeError: Cannot read properties of undefined (reading 'storeNames')
at TimelineReader.readById (hydrogen-web\target\lib-build\hydrogen.cjs.js:12483:33)
at Timeline._getEventFromStorage (hydrogen-web\target\lib-build\hydrogen.cjs.js:12762:46)
at Timeline._loadContextEntryNotInTimeline (hydrogen-web\target\lib-build\hydrogen.cjs.js:12747:35)
at Timeline._loadContextEntriesWhereNeeded (hydrogen-web\target\lib-build\hydrogen.cjs.js:12741:14)
at Timeline.addEntries (hydrogen-web\target\lib-build\hydrogen.cjs.js:12699:10)
at mountHydrogen (4-hydrogen-vm-render-script.js:204:12)
at 4-hydrogen-vm-render-script.js:353:1
at Script.runInContext (node:vm:139:12)
at _renderHydrogenToStringUnsafe (matrix-public-archive\server\hydrogen-render\3-render-hydrogen-to-string-unsafe.js:102:41)
at async process.<anonymous> (matrix-public-archive\server\hydrogen-render\2-render-hydrogen-to-string-fork-script.js:18:27)
```
Split off from https://github.com/matrix-org/matrix-public-archive/pull/43
Listen to `process.on('uncaughtException', ...)` and handle the async errors ourselves so it no longer fails the child process.
And if the process does exit with status code 1 (error), we have those underlying errors serialized and shown.
We now run the Hydrogen render in a `child_process` so we can exit the whole render process. We still use the `vm` to setup the browser-like globals. With a `vm`, everything continues to run even after it returns and there isn't a way to clean up, stop, kill, terminate the vm script or context so we need this extra `child_process` now to clean up. I don't like the complexity necessary for this though. I wish the `vm` API allowed for this use case. The only way to stop a `vm` is the `timeout` and we want to stop as soon as we return.
Fix https://github.com/matrix-org/matrix-public-archive/issues/34
Eric Eastwood