deno check w/ byonm shows resolver error for micromatch npm package

[dsherret]

// main.ts
import * as foo from "npm:[email protected]";

console.log(foo);

{
  "unstable": ["byonm"]
}

{
  "dependencies": {
    "micromatch": "^4.0.5"
  }
}

1. npm install
2. deno run main.ts -- ok
3. deno run --check main.ts -- fail

% deno run --check main.ts
error: Failed resolving types. Failed resolving package subpath for 'npm:[email protected]' in '/Users/david/dev/scratch/node_modules/micromatch'.
    at file:///Users/david/dev/scratch/main.ts:1:22

% deno info main.ts
local: /Users/david/dev/scratch/main.ts
emit: /Users/david/Library/Caches/deno/gen/file/Users/david/dev/scratch/main.ts.js
type: TypeScript
dependencies: 1 unique
size: 63B

file:///Users/david/dev/scratch/main.ts (63B)
├── file:///Users/david/dev/scratch/node_modules/micromatch/index.js (unknown)
└── Failed resolving package subpath for 'npm:[email protected]' in '/Users/david/dev/scratch/node_modules/micromatch'. (resolve error)
scratch % deno run --check main.ts
error: Failed resolving types. Failed resolving package subpath for 'npm:[email protected]' in '/Users/david/dev/scratch/node_modules/micromatch'.
    at file:///Users/david/dev/scratch/main.ts:1:22