Error Handling: setup error handling across the app

[Alex-Cannon]

Needs #52 #53 to start work on this.

Any call to getGoogleSheet should be handled globally. This way we can keep track of errors more easily and output them to the admin's error page.

This is how things should work after this PR:

1. When the app loads, the entire google sheet is pulled. This is available globally.
2. After we get the google sheet, we need to test every category / service to make sure it is valid (not missing a category, has correct references, etc.) Utils for this will be done in Error handling: Extract and test sheet validation logic #52
3. If a category / service is invalid, it will be removed from the results and the error will be logged on the /errors page, where admins can see warnings and errors about the sheet. See Error Handling: Create base Error page #53
4. A link should appear on the home page with text along the lines of: "There was an error processing your data. Site admins please see the /errors page" (There should already be a component for this)