fix: Reassign alias language id safely

[MonkeyDo]

Fix issue with language property being reassigned by object destructuring (introduced in PR #308 ).
Also refactor other entities to use the same protection (use languageID instead of language.id in case language is undefined)

[coveralls]

Coverage remained the same at 43.014% when pulling a7f873b on fix-alias-id into 6914c74 on master.

[MonkeyDo]

@panwarabhishek345 For your information, I found a bug pr #308 that I hadn't seen coming !
Basically, with {language: languageID, …rest}, we assign language, but if language is present in rest, it gets reassigned by …rest.
So instead, we should destructure rest first, and only after that, reassign language.

[panwarabhishek345]

True, I should have taken care of that.

[MonkeyDo]

I didn't see it at all, neither during review nor testing, which means I didn't test well enough on my side !

It's a sneaky one, hard to see when using object destructuring !