Cannot invoke an object which is possibly 'undefined'

I'm not sure if this is intended, but the .rebuild() method from the BuildResult interface, accordingly to the snippet below, can also be undefined:

esbuild/lib/types.ts

Line 88 in 2fa473e

rebuild?: (() => Promise<BuildResult>) & { dispose(): void }; // Only when "incremental" is true

Because of this, is necessary to adhere to some hacky solutions like this:

const buildResult = await esbuildService.build({ ...esbuildConfig, incremental: true })
buildResult.rebuild!() // non-null assertions defeats the purpose of using "strict: true" on tsconfig.json

or also:

const buildResult = await esbuildService.build({ ...esbuildConfig, incremental: true })
buildResult.rebuild && buildResult.rebuild()

or even this:

const buildResult = await esbuildService.build({ ...esbuildConfig, incremental: true })
buildResult.rebuild?.call(this)

Is there anything that i'm missing? as shown in the example from 0.8.12 release https://github.com/evanw/esbuild/blob/master/CHANGELOG.md), there were no need for any checking to use the .rebuild() method

require('esbuild').build({
  entryPoints: ['app.js'],
  bundle: true,
  outfile: 'out.js',
  incremental: true,
}).then(result => {
  // The "rebuild" method is present if "incremental" is true. It returns a
  // promise that resolves to the same kind of object that "build" returns.
  // You can call "rebuild" as many times as you like.
  result.rebuild().then(result2 => {
    // Call "dispose" when you're done to free up resources.
    result.rebuild.dispose()
  })
})

[tsugabloom]

It says

"The rebuild method is present if "incremental" is true

So that's why it's undefined. You might be able to do some TypeScript hackery to return a version of BuildResult with that one property added as non-optional, but I don't know if it's worth it since ! works. It's also not the only field that has conditional behaviour like this, see "outputFiles" on the same interface.