fix: do nothing if target does not exist in getters map

[karrui]

#153 introduced the getters map to allow for multiple hooks. However, there may exist edge cases where the name does not exist in the target, resulting in the following error:

/project/path/node_modules/import-in-the-middle/lib/register.js:20
    return getters.get(target)[name]()
                                    ^

TypeError: getters.get(...)[name] is not a function
    at Object.get (/project/path/node_modules/import-in-the-middle/lib/register.js:20:37)
    at /project/path/node_modules/dd-trace/packages/datadog-instrumentations/src/helpers/hook.js:41:40
    at callHookFn (/project/path/node_modules/import-in-the-middle/index.js:29:22)
    at Hook._iitmHook (/project/path/node_modules/import-in-the-middle/index.js:150:11)
    at /project/path/node_modules/import-in-the-middle/lib/register.js:37:31
    at Array.forEach (<anonymous>)
    at register (/project/path/node_modules/import-in-the-middle/lib/register.js:37:15)
    at file:///project/path/node_modules/vitest/dist/chunks/base.BlXpj3e_.js?iitm=true:122:1
    at ModuleJob.run (node:internal/modules/esm/module_job:222:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:323:24)

Node.js v20.12.2

I am unable to trace why this happens, and thus am unable to create a test case. However, a hooked package resulted in the following target and name values when I logged it.

console.log(JSON.stringify(target), name) // {} default

typeof getters.get(target)[name] could also be undefined and cause a type error. I've made the type check stricter before invoking the function.

See DataDog/dd-trace-js#4713 (comment) for context

[timfish]

Sorry the changes are causing issues, the test cases and libraries we cover are quite extensive!

Do you know what library or module cause this? I see a couple of large projects linked that I can test.

[karrui]

Feel free to fork https://github.com/opengovsg/starter-kit and test. The current vitest tests are failing due to v1.11.1.

[timfish]

I haven't debugged this yet but guess this is caused by the code checking for a default export and there is none so it should return undefined rather than throw.

[timfish]

I think a suitable test case could be added to the the end of test I added and it would check for an export that doesn't exist and confirm it's undefined without throwing.

const imp = await import('../fixtures/foo.mjs')

strictEqual(imp.foo(), 'foo-first-second')
// This should not throw!
strictEqual(imp.doesNotExist, undefined)

[karrui]

I think a suitable test case could be added to the the end of test I added and it would check for an export that doesn't exist and confirm it's undefined without throwing.

const imp = await import('../fixtures/foo.mjs')

strictEqual(imp.foo(), 'foo-first-second')
// This should not throw!
strictEqual(imp.doesNotExist, undefined)

That test case does not fail even before this fix, so might not be useful to add!

[karrui]

Found a test case that passes with this fix but not previously. Unsure if that's expected behaviour though. Will leave it to you to decide

[bizob2828]

I have confirmed this PR fixes the issue detailed in here. I know I don't have approver rights but I work with @jsumners who is on vacation

[timfish]

Thanks @bizob2828. We had agreed on at least 2 approvals before merging so I'd still like an approval from another maintainer before merging!

[pichlermarc]

Looks good, thanks for fixing this 👍