Merge pull request #163 from bdach/better-tool-location-failure-messa…

…ging

Improve error messaging when locating tools fails

Program.cs

@@ -678,13 +678,17 @@ private static string getToolPath(string packageName, string toolExecutable)
         {
             var process = Process.Start(new ProcessStartInfo("dotnet", "list osu.Desktop.Deploy.csproj package")
             {
-                RedirectStandardOutput = true
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
             });
 
             Debug.Assert(process != null);
 
             process.WaitForExit();
 
+            if (process.ExitCode != 0)
+                throw new InvalidOperationException($"Could not locate tool {toolExecutable}!\nStandard error: {process.StandardError.ReadToEnd()}");
+
             string output = process.StandardOutput.ReadToEnd();
 
             var match = Regex.Matches(output, $@"(?m){packageName.Replace(".", "\\.")}.*\s(\d{{1,3}}\.\d{{1,3}}\.\d.*?)$");