The ShEx editor should have syntax highlighting for the Shape Expressions.
I mocked up using the ace ShExC mode in an EntitySchema.
The [x]s at the left come form an WebWorker which runs a shex.js ShEx parser asynchronously. If you uncomment the PREFIX decl at the top of the schema, you'll see the [x]s go away in ~.2 seconds.
Upsides: syntax highlighting and error checking.
Downsides: no tool tips for Qids.
I think @Jelabra has a student working one that's more in the spirit of the wikidata SPARQL editor, which will probably be more useful in the long run. OTOH, you could use mine today and switch to his when it's ready.