feat: create flowcharts from a generic element using elbow arrows (#8329)

Co-authored-by: Mark Tolmacs <mark@lazycat.hu>
Co-authored-by: dwelle <5153846+dwelle@users.noreply.github.com>

packages/excalidraw/utils.ts

@@ -929,6 +929,12 @@ export const assertNever = (
   throw new Error(message);
 };
 
+export function invariant(condition: any, message: string): asserts condition {
+  if (!condition) {
+    throw new Error(message);
+  }
+}
+
 /**
  * Memoizes on values of `opts` object (strict equality).
  */