TootComposer: fix random stmt may be empty

package.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://json.schemastore.org/package",
   "name": "tutu",
-  "version": "1.0.6",
+  "version": "1.0.7",
   "description": "",
   "private": true,
   "type": "module",

src/timelines/TootComposer.tsx

@@ -183,7 +183,7 @@ function randomChoose<T extends any[]>(
   rn: number,
   K: T,
 ): T extends Array<infer E> ? E : never {
-  const idx = Math.round(rn * K.length);
+  const idx = Math.round(rn * K.length) - 1;
   return K[idx];
 }