Fixed typescript error

client/package-lock.json

@@ -16073,6 +16073,11 @@
       "resolved": "https://registry.npmjs.org/typedarray/-/typedarray-0.0.6.tgz",
       "integrity": "sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c="
     },
+    "typescript": {
+      "version": "3.7.5",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-3.7.5.tgz",
+      "integrity": "sha512-/P5lkRXkWHNAbcJIiHPfRoKqyd7bsyCma1hZNUGfn20qm64T6ZBlrzprymeu918H+mB/0rIg2gGK/BXkhhYgBw=="
+    },
     "uglify-js": {
       "version": "3.4.10",
       "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.4.10.tgz",

client/package.json

@@ -68,6 +68,7 @@
     "style-loader": "1.0.0",
     "terser-webpack-plugin": "1.4.1",
     "ts-pnp": "1.1.4",
+    "typescript": "^3.7.5",
     "url-loader": "2.1.0",
     "webpack-dev-server": "3.2.1",
     "webpack-manifest-plugin": "2.1.1",