Add web front-end and fix API issues

node_modules/concurrently/dist/lib/assert.d.ts

@@ -0,0 +1,10 @@
+/**
+ * Asserts that some condition is true, and if not, prints a warning about it being deprecated.
+ * The message is printed only once.
+ */
+export declare function assertDeprecated(check: boolean, name: string, message: string): void;
+/**
+ * Asserts that some condition is true, and if not, prints a warning about the runtime not being well supported.
+ * The message is printed only once.
+ */
+export declare function assertNotRuntime(check: boolean, name: string, message: string): void;