Provide more informative error on non-supported resources

[peterdesmet]

When reading a non-tabular resource, frictionless-r returns an error:

library(frictionless)
x <- read_package("https://raw.githubusercontent.com/peterdesmet/traffic-signs-hansbeke/refs/heads/master/datapackage.json")
read_resource(x, "traffic-signs-hansbeke")
#> Error in `get_schema()`:
#> ! Resource "traffic-signs-hansbeke" must have a profile property with
#>   value "tabular-data-resource".

^{Created on 2025-05-20 with reprex v2.1.1}

This error should probably rephrased, since the resource might be perfectly valid, but just not at a tabular one.