Add custom exception for errors from Yaml Validator Library (#706)

src/YamlValidator/SchemaLoader.cs

@@ -22,7 +22,7 @@ public JsonSchema Load()
             var assemblyName = assembly.GetName().Name;
             if (fileStream == null)
             {
-                throw new IOException($"Resource {file} could not found in assembly {assemblyName}");
+                throw new YamlValidatorLibraryException($"The schema could not be loaded from assembly.");
             }
             using var streamReader = new StreamReader(fileStream);
             var jsonSchemaString = streamReader.ReadToEnd();
@@ -45,7 +45,7 @@ public JsonSchema Load()
         }
         if (node == null)
         {
-            throw new InvalidDataException("Schema was not able to be read into memory");
+            throw new YamlValidatorLibraryException("The schema could not be serialized from the assembly.");
         }
         return node;
     }

src/YamlValidator/ValidatorError.cs

@@ -31,9 +31,9 @@ public override string ToString()
             foreach (var error in Errors)
             {
                 var errType = string.IsNullOrEmpty(error.Key) ? "Error" : error.Key;
-                errString += $"\t{errType}: {error.Value}\n";
+                errString += $"\t\t- {errType}: {error.Value}\n";
             }
         }
-        return $"InstanceLocation: {InstanceLocation}\nSchemaPath: {SchemaPath}\nErrors:\n{errString}";
+        return $"\t- InstanceLocation: {InstanceLocation}\n\t- SchemaPath: {SchemaPath}\n\t- Errors:\n{errString}";
     }
 }

src/YamlValidator/YamlValidatorLibraryException.cs

@@ -0,0 +1,10 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+namespace Microsoft.PowerPlatform.PowerApps.Persistence.YamlValidator;
+public class YamlValidatorLibraryException : Exception
+{
+    public YamlValidatorLibraryException(string reason) : base(message: reason)
+    {
+    }
+}