Running the following produces the following error.
$ deno run --importmap=import-map.json index.ts
Compile file:///Users/john/Documents/code/deno/bins/greenlet-experiments/index.ts error: Uncaught Other: Is a directory (os error 21) ► $deno$/dispatch_json.ts:40:11 at DenoError ($deno$/errors.ts:20:5) at unwrapResponse ($deno$/dispatch_json.ts:40:11) at sendAsync ($deno$/dispatch_json.ts:91:10)