Changes to schema file cause panics

[rbalicki2]

On Ubuntu (mint) with an encrypted file system, you cannot modify the schema, because a modification results in a delete followed by a create, and we error if the schema is deleted.

Oddly, the behavior is different for non-schema files. e.g. I would expect to see an invalid compilation, followed by a valid compilation, when a file containing an isograph literal is modified. Hence, I think there's a possibility that there's a difference in behavior in categorize_and_filter_events between schema and non-schema files. But that doesn't seem to be the case!

It's mysterious

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EDIT: I just repro'd this on a mac. When I save a file via VSCode, I see no errors. But if I do git checkout head -- ./demos, I can consistently cause this issue to arise:

Handling schema update Remove("/Users/rbalicki/code/isograph/demos/pet-demo/backend/schema.graphql")
Handling schema update CreateOrModify("/Users/rbalicki/code/isograph/demos/pet-demo/backend/schema.graphql")
Handling schema update CreateOrModify("/Users/rbalicki/code/isograph/demos/pet-demo/backend/schema.graphql")
  ERROR  Error when compiling.

Schema file not found. Cannot proceed without a schema.
Compilation took 0ms.