creature target spells

[Hilary]

Some spells only target creatures.

Could you use those spells to determine if a statue is a petrified person or if a chest is a mimic?

[Jerrykhor]

I know what you're thinking: Does it work like a video game where if i use an ability on an invalid target, an error message pops up?

I highly doubt any DM would run it like that. Most DM would let you Eldritch Blast objects anyway even though by RAW they only target creatures.

[MaxWilson]

Some spells only target creatures.

Could you use those spells to determine if a statue is a petrified person or if a chest is a mimic?

FWIW, Xanathar's has an optional rule which encourages DMs to let the spell silently fail as if the target had made its save. The example given is "humanoid-only spell like Charm Person on a vampire: will behave identically to if the target saved", but a similar logic might apply to create vs. object.

Or perhaps your DM will just let the spell work on objects as well as creatures. There are certainly cases where I do that, e.g. I let Eldritch Blast blast whatever. I figure if it was genuinely supposed to not affect objects, it would be Psychic damage instead of Force damage.

Ultimately, you need to ask your DM for a ruling and then stick to it.