Strange error message when reading RNTuples

[jminguezCern]

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Description

I was trying with a minimal script to check the error messages that RDataFrame throws for example when trying to read a RNTuple with an incorrect name from a root file.

Reproducer

#include "ROOT/RDataFrame.hxx"
#include <iostream>

int main() {
    try {
        ROOT::RDataFrame rdf("a", "output.root");
        auto cols = rdf.GetColumnNames();
        std::cout << cols.size() << "\n";
    } catch (const std::exception &e) {
        std::cerr << "Error opening 'a' in 'output.root': " << e.what() << "\n";
        return 1;
    }
    return 0;
}

Getting this error message:
Error opening 'a' in 'output.root': RDataFrame: unsupported data format for dataset "a" in file "output.root".

ROOT version

ROOT Version: 6.39.01

Installation method

Build from source

Operating system

Linux Ubuntu

Additional context

No response

[dpiparo]

Hi,

What is a exactly? We routinely run tutorials and tests in our CI reading RNTuple instances from RDF.

[jminguezCern]

It is just a name for a RNTuple that it is not present in my root file, so I can force the error.