[bugfix] don't fallback on wineprefix and show error on mod install

assets/jsons/translations/en.json

@@ -588,7 +588,8 @@
                 "msg": {
                     "success": "All mods have been uninstalled.",
                     "errors": {
-                        "no-mods": "No mods are installed in this version 😑"
+                        "no-mods": "No mods are installed in this version 😑",
+                        "no-wineprefix": "Could not find BSManager WINEPREFIX path, please launch beat saber in BSManager first."
                     }
                 }
             },

src/main/services/mods/bs-mods-manager.service.ts

@@ -158,11 +158,10 @@ export class BsModsManagerService {
             winePath = `"${winePathResult}"`;
 
             const winePrefix = this.linuxService.getWinePrefixPath();
-            if (winePrefix) {
-                env.WINEPREFIX = winePrefix;
-            } else {
-                log.warn("Could not find BSManager WINEPREFIX path, using system's default value instead");
+            if (!winePrefix) {
+                throw new CustomError("Could not find BSManager WINEPREFIX path", "no-wineprefix");
             }
+            env.WINEPREFIX = winePrefix;
         }
 
         return new Promise<boolean>(resolve => {