[BUG]: Misuse of variable in UID function fails silently

[MichelDiz]

What version of Dgraph are you using?

latest

Tell us a little more about your go-environment?

N/A

Have you tried reproducing the issue with the latest release?

Yes

What is the hardware spec (RAM, CPU, OS)?

N/A

What steps will reproduce the bug?

Run a query like this

q(func: uid(val(A)) )

Expected behavior and actual result.

q(func: uid(val(A)) ) = Silent return it should fail

q(func: uid(A) ) = Correct one.

Additional information

No response

[github-actions]

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