Added basic errors for stats clients

ref #56

src/errors/StatsClientErrors.ts

@@ -0,0 +1,25 @@
+import { IsString } from 'class-validator';
+import { NotAcceptableError, NotFoundError } from 'routing-controllers';
+
+/**
+ * Error to throw, when a non-existant stats client get's loaded.
+ */
+export class StatsClientNotFoundError extends NotFoundError {
+	@IsString()
+	name = "StatsClientNotFoundError"
+
+	@IsString()
+	message = "The stats client you provided couldn't be located in the system. \n Please check your request."
+}
+
+/**
+ * Error to throw when two stats clients' ids don't match.
+ * Usually occurs when a user tries to change a stats client's id.
+ */
+export class StatsClientIdsNotMatchingError extends NotAcceptableError {
+	@IsString()
+	name = "StatsClientIdsNotMatchingError"
+
+	@IsString()
+	message = "The ids don't match! \n And if you wanted to change a stats client's id: This isn't allowed!"
+}