improve error msg

Author: chtenb

Rubjerg.Graphviz/GraphvizCommand.cs

@@ -45,7 +45,7 @@ internal static string Rid
         ];
         return possibleLocations.Select(dir => Path.Combine(dir, "dot")).FirstOrDefault(File.Exists)
             ?? possibleLocations.Select(dir => Path.Combine(dir, "dot.exe")).FirstOrDefault(File.Exists)
-            ?? throw new InvalidOperationException("Could not find path to dot binary");
+            ?? throw new InvalidOperationException("Could not find path to dot binary in any of: " + string.Join(", ", possibleLocations));
     });
     internal static string DotExePath => _DotExePath.Value;