merged with main

src/utils/invariant.ts

@@ -0,0 +1,18 @@
+export function invariant<T = unknown>(
+  condition: T,
+  errorMessage?: ((condition: T) => string) | string,
+): asserts condition {
+  if (condition) {
+    return;
+  }
+
+  if (typeof errorMessage === 'undefined') {
+    throw new Error('Invariant failed');
+  }
+
+  if (typeof errorMessage === 'string') {
+    throw new Error(errorMessage);
+  }
+
+  throw new Error(errorMessage(condition));
+}