GH-2100 - /config doesn't show message when file doesn't exist

src/GitVersionCore.Tests/NamedConfigFileLocatorTests.cs

@@ -136,6 +136,20 @@ public void NoWarnOnCustomYmlFileOutsideRepoPath()
             stringLogger.Length.ShouldBe(0);
         }
 
+        [Test]
+        public void ThrowsExceptionOnCustomYmlFileDoesNotExist()
+        {
+            var sp = GetServiceProvider(arguments);
+            configFileLocator = sp.GetService<IConfigFileLocator>();
+
+            var exception = Should.Throw<WarningException>(() => { configFileLocator.Verify(workingPath, repoPath); });
+
+            var workingPathFileConfig = Path.Combine(workingPath, arguments.ConfigFile);
+            var repoPathFileConfig = Path.Combine(repoPath, arguments.ConfigFile);
+            var expectedMessage = $"The configuration file was not found at '{workingPathFileConfig}' or '{repoPathFileConfig}'";
+            exception.Message.ShouldBe(expectedMessage);
+        }
+
         private string SetupConfigFileContent(string text, string fileName = null, string path = null)
         {
             if (string.IsNullOrEmpty(fileName)) fileName = ((NamedConfigFileLocator)configFileLocator).FilePath;

src/GitVersionCore/Configuration/NamedConfigFileLocator.cs

@@ -46,6 +46,11 @@ private void WarnAboutAmbiguousConfigFileSelection(string workingDirectory, stri
             {
                 throw new WarningException($"Ambiguous config file selection from '{workingConfigFile}' and '{projectRootConfigFile}'");
             }
+
+            if (!hasConfigInProjectRootDirectory && !hasConfigInWorkingDirectory)
+            {
+                throw new WarningException($"The configuration file was not found at '{workingConfigFile}' or '{projectRootConfigFile}'");
+            }
         }
     }
 }