Add SSE Session class

source/errors.ts

@@ -1,3 +1,23 @@
+/**
+ * Error thrown when a response body is null
+ */
+export class ResponseBodyNullError extends Error {
+    constructor() {
+        super('Response body is null');
+        this.name = 'ResponseBodyNullError';
+    }
+}
+
+/**
+ * Error thrown when an HTTP error occurs
+ */
+export class HTTPError extends Error {
+    constructor(status: number, message: string) {
+        super(`HTTP error! Status: ${status} - ${message}`);
+        this.name = 'HTTPError';
+    }
+}
+
 /**
  * Error thrown when the maximum number of retries is hit in an exponential backoff
  */