fix!: Don't log potentially sensitive value in Value::validate

[Kriskras99]

This is done by removing the logging completely and returing an error instead of a boolean. The code will also no longer panic when it fails to resolve the schema.

This is a breaking change, users can fix their code by adding .is_ok() to get the previous behaviour.

Reported-by: CodeQL

[martin-g]

IIRC this has been requested by someone to be able to debug validation issues. They said that it is hard to debug such issues when using big/huge schemas. The actual request was to print the path to the failing field but this was rather complex to implement.

Maybe log it as a trace ?! Or log only when debug_assertions is enabled ?!
Or make it configurable ?!
Or use custom Debug/Display/our-own impl that skips (sensitive) values ?!

[Kriskras99]

I was already thinking about adding the path to the error. So I'll try that!

[Kriskras99]

I still need to do schema, but here is a sample of improved error messages (top is new, bottom is old):

The value is invalid for the given schema: Unsupported value-schema combination! Value: Record.b.Record.z.Null, schema: Int
The value is invalid for the given schema: Unsupported value-schema combination! Value: Null, schema: Int

The value is invalid for the given schema: Unsupported value-schema combination! Value: Record.b.String, schema: Record(RecordSchema { name: Name { name: "Inner", .. }, fields: [RecordField { name: "z", schema: Int, .. }], .. })
The value is invalid for the given schema: Unsupported value-schema combination! Value: String("testing"), schema: Record(RecordSchema { name: Name { name: "Inner", .. }, fields: [RecordField { name: "z", schema: Int, .. }], .. })

The value is invalid for the given schema: Unsupported value-schema combination! Value: Record.a.Boolean, schema: Long
The value is invalid for the given schema: Unsupported value-schema combination! Value: Boolean(false), schema: Long

The value is invalid for the given schema: Enum("spades") is not at position 1 in the schema
The value is invalid for the given schema: Symbol 'spades' is not at position '1'

The value is invalid for the given schema: Size of Fixed (5) is different than the schema's size (4)
The value is invalid for the given schema: The value's size (5) is different than the schema's size (4)

Invalid value: Int(42) for schema: Boolean. Reason: Unsupported value-schema combination! Value: Int(42), schema: Boolean
Invalid value: Int(42) for schema: Boolean. Reason: Unsupported value-schema combination! Value: Int, schema: Boolean

Value Int(1) does not match schema String: Reason: Unsupported value-schema combination! Value: Int, schema: String
Value Int(1) does not match schema String: Reason: Unsupported value-schema combination! Value: Int(1), schema: String

You'll notice that when the actual value (1, True, "Some string") is not relevant to the error, it is not in included.

It costs a bit of extra stack space and two extra references being passed to validate_internal, one for tracking the value path and one for tracking the schema path. There are no heap allocations and it writes the path directly into the format! string.

[martin-g]

Would be possible to print the name for named schemas ? E.g. Record[ns.myname].a.Boolean

[Kriskras99]

Absolutely, I was thinking of Record{name}. But that is only possible for the schema oath as Value doesn't store a name.

[Kriskras99]

Schema path is now also added. I think this would also be useful in the errors for the serializer and deserializer. Let me know what you think.