chore(build): update build scripts to ensure proper package building

Author: ThornWalli

package.json

@@ -24,8 +24,9 @@
     "packages/observables/package.json"
   ],
   "scripts": {
-    "postinstall": "npm run build",
-    "build": "npm run build --workspaces",
+    "postinstall": "npm run build:packages",
+    "build": "npm run build:packages",
+    "build:packages": "npm run build --workspaces --if-present",
     "lint": "npm run lint:es",
     "lint:es": "eslint --flag unstable_native_nodejs_ts_config .",
     "prepare": "husky",