Error when calling async runModel with empty inputs array

[chrispcampbell]

This is a bit of an edge case, since most models will have at least one input, but in the case where runModel (specifically the async runner implementation) is called with an empty inputs array, it produces an error:

 FAIL  src/runnable-model/buffered-run-model-params.spec.ts > BufferedRunModelParams > should copy inputs
TypeError: Cannot convert undefined or null to object
 ❯ BufferedRunModelParams.copyInputs src/runnable-model/buffered-run-model-params.ts:122:11
    120| 
    121|     // Copy from the internal buffer to the a…
    122|     array.set(this.inputs.view)
       |           ^
    123|   }
    124| 
 ❯ src/runnable-model/buffered-run-model-params.spec.ts:172:12

 FAIL  tests/runner.spec.ts > spawnAsyncModelRunner (with mock 'js' model) > should run the model (with empty inputs array)
TypeError: Cannot convert undefined or null to object
 ❯ runModel dist/index.cjs:103:19
 ❯ ../../node_modules/.pnpm/[email protected]/node_modules/threads/dist/worker/index.js:109:26
 ❯ ../../node_modules/.pnpm/[email protected]/node_modules/threads/dist/worker/index.js:8:71
 ❯ __awaiter ../../node_modules/.pnpm/[email protected]/node_modules/threads/dist/worker/index.js:4:12
 ❯ runFunction ../../node_modules/.pnpm/[email protected]/node_modules/threads/dist/worker/index.js:106:12

[chrispcampbell]

The fix is to check for an empty (internal) inputs buffer in BufferedRunModelParams and skip the copy if the buffer is empty. This is the same approach we used for the outputIndices buffer.

I will add tests for both RunModelParams implementations as well as for the synchronous and async ModelRunner implementations.