onLine = ( line, index, lines ) => {
			// be strict: output is just one single line (in a single onData stdout callback)
			if ( index !== 0 || lines.length !== 1 ) {
				reject( new LogError( "Unexpected version check output", lines ) );
				return;
			}

			// match the version string
			const match = regexp.exec( line );
			if ( match && match[ 1 ] ) {
				resolve( match[ 1 ] );
			} else {
				reject( new LogError( "Invalid version check output", lines ) );
			}
		}
Validate
Runs the executable with the `--version` parameter and reads answer from stderr
@param {ExecObj} execObj
@param {Object} providerConfData
@param {string} providerConfData.type
@returns {Promise}