Add Event Emitter

source/errors.ts

@@ -0,0 +1,9 @@
+/**
+ * Error thrown when a waitFor timeout is reached
+ */
+export class WaitForTimeoutError extends Error {
+    constructor(type: string) {
+        super(`Timeout waiting for event "${type}"`);
+        this.name = 'WaitForTimeoutError';
+    }
+}