Failed on Linux about flutterfire_desktop HOT 4 OPEN

Building Linux application...
[ +9 ms] <- compile package:pathfinder/main.dart
[ +1 ms] executing: [build/linux/x64/debug/] cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DFLUTTER_TARGET_PLATFORM=linux-x64 /home/steve/Documents/GitHub/dfc/dashboard/linux
[ +55 ms] -- Checking for module 'webkit2gtk-4.0'
[ +9 ms] -- No package 'webkit2gtk-4.0' found
[ ] -- Configuring incomplete, errors occurred!

from flutterfire_desktop.

Strangely I had reported the same issue to another repo in 2019. I got a new computer since then...

Solutions are here:
webview/webview#230

Put this in your docs:

Debian: sudo apt install libwebkit2gtk-4.0-dev

from flutterfire_desktop.

Now I'm getting this:
Launching lib/main.dart on Linux in debug mode...
lib/main.dart:1
CMake Error at cmake_install.cmake:61 (file):
file INSTALL cannot copy file
"/home/steve/Documents/GitHub/dfc/dashboard/build/linux/x64/debug/intermediates_do_not_run/dashboard"
to "/usr/local/dashboard".

Exception: Build process failed
Exited (sigterm)

from flutterfire_desktop.

strangely, flutter clean (twice) fixed that last problem. Now another:

[ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: MissingPluginException(No implementation found for method Firebase#initializeCore on channel plugins.flutter.io/firebase_core)
#0 MethodChannel._invokeMethod
package:flutter/…/services/platform_channel.dart:165

#1 MethodChannel.invokeListMethod
package:flutter/…/services/platform_channel.dart:353

#2 MethodChannelFirebase._initializeCore
package:firebase_core_platform_interface/…/method_channel/method_channel_firebase.dart:31

#3 MethodChannelFirebase.initializeApp
package:firebase_core_platform_interface/…/method_channel/method_channel_firebase.dart:73

#4 Firebase.initializeApp
package:firebase_core/src/firebase.dart:40

#5 Main.start
package:shared_ui/src/main.dart:31

from flutterfire_desktop.