fix: unknownApp name for Expo apps

Author: IjzerenHein

src/react-native-bundle-visualizer.js

@@ -10,7 +10,7 @@ const { explore } = require('source-map-explorer');
 const pkgJSON = JSON.parse(fs.readFileSync('./package.json'));
 
 function sanitizeString(str) {
-  return str.replace(/[^\w]/gi, '');
+  return str ? str.replace(/[^\w]/gi, '') : str;
 }
 
 function getAppName() {

test/Expo35/app.json

@@ -1,6 +1,6 @@
 {
   "expo": {
-    "name": "Bundle Visualizer",
+    "name": "Expo35",
     "slug": "Expo35",
     "privacy": "public",
     "sdkVersion": "36.0.0",

test/Expo42/app.json

@@ -1,6 +1,6 @@
 {
   "expo": {
-    "name": "Bundle Visualizer",
+    "name": "Expo42",
     "slug": "Expo42",
     "version": "1.0.0",
     "orientation": "portrait",