Patch validation errors are swallowed (defaults to `ScimErrorInvalidValue`)

[Achooo]

Issue

Patch validation errors get swallowed up to ScimErrorInvalidValue here:

scim/resource_type.go

Lines 158 to 160 in 172bf2a

	value, err := validator.Validate()
	if err != nil {
	return nil, &errors.ScimErrorInvalidValue

Example

Hence, the ScimType for errors upon patch validation is not always respected, for example:

    { "schemas":
           ["urn:ietf:params:scim:api:messages:2.0:PatchOp"],
         "Operations":[
           {
            "op":"remove",
            "path":"",
            "value":"newusername"
           }]
    }

In this example, a remove path must be provided and as per the RFC and we should return a scimType of noTarget:

If "path" is unspecified, the operation fails with HTTP status code 400 and a "scimType" error code of "noTarget".

Although the code does actually do this validation here

scim/internal/patch/remove.go

Lines 15 to 20 in 172bf2a

	if v.Path == nil {
	return nil, &errors.ScimError{
	ScimType: errors.ScimTypeNoTarget,
	Status: http.StatusBadRequest,
	}
	}

, it gets swallowed in validatePatch.

The same issue is seen for other validations (e.g. sometimes a SyntaxError is swallowed).