Angular async pipe return type is 'string|null' not 'string' as [highlight] expect. about ngx-highlightjs

[jasomimo]

Hi @MurhafSousli, I experienced same issue as @konradkurylo with "strictTemplates": true option in angularCompilerOptions, tsconfig.json.

I don't think there is a need to for a new pipe, but the highlight directive should already handle if the value is null, which is possible return value from async pipe.

In the ngOnChanges of highlight.ts, there is already check for currentValue !== null.

I believe @Input('highlight') code!: string; could be changed to @Input('highlight') code!: string | null; and that should fix the error and hopefully don't break anything.

I like you package and I'm happy to open PR, if you would agree with the change.

[MurhafSousli]

@jasomimo In this case, you need to remove the bang from the variable because it means the variable will not be null, as explained here

https://stackoverflow.com/questions/42273853/in-typescript-what-is-the-exclamation-mark-bang-operator-when-dereferenci

Try to verify if this fixes the issue or if other variables need to be updated the same way!

Thanks a lot!

[MurhafSousli]

Sorry for the late, v6.1.3 has been published! please let me know if the issue is fixed!

[MurhafSousli]

Please add reproduction here https://stackblitz.com/edit/ngx-highlightjs! You seem to have strict type template on your end.. I don't think there is a need for another pipe

[jasomimo]

@MurhafSousli I've updated highlight.ts to accept also null as valid value. I saw there is already a test for null value, so I didn't add a new one. Change is available for a review in PR: #225

I tested ngx-highlightjs with this change in my project, where I was previously getting error and the fix worked well.

Looking forward to the feedback, if this works for you.