Compilation error on Flutter

[emzee1]

Hi Jexos
Its awesome app. I intend to do a little modifications, but the app is not compiling on flutter. Initially it is giving error of embedding version, and later fails to compile on a complex error. Can you guide about compilation?
detail error is as under:
flutter build apk --release --ignore-deprecation
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Warning
──────────────────────────────────────────────────────────────────────────────
Your Flutter application is created using an older version of the Android
embedding. It is being deprecated in favor of Android embedding v2. Follow the
steps at

https://flutter.dev/go/android-project-migration

to migrate your project. You may also pass the --ignore-deprecation flag to
ignore this check and continue with the deprecated v1 embedding. However,
the v1 Android embedding will be removed in future versions of Flutter.
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
The detected reason was:

/home/asmi/snap/khanos/android/app/src/main/AndroidManifest.xml uses android:name="io.flutter.app.FlutterApplication"
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Running "flutter pub get" in khanos... 11.0s
This app is using a deprecated version of the Android embedding.
To avoid unexpected runtime failures, or future build failures, try to migrate this app to the V2 embedding.
Take a look at the docs for migrating an app: https://github.com/flutter/flutter/wiki/Upgrading-pre-1.12-Android-projects

Building without sound null safety
For more information see https://dart.dev/null-safety/unsound-null-safety

../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/boardview-0.2.2/lib/board_item.dart:92:20: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.

'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../flutter/common/flutter/packages/flutter/lib/src/widgets/binding.dart').
WidgetsBinding.instance!
^
../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/boardview-0.2.2/lib/boardview.dart:307:22: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../flutter/common/flutter/packages/flutter/lib/src/widgets/binding.dart').
WidgetsBinding.instance!.addPostFrameCallback((Duration duration) {
^
../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/boardview-0.2.2/lib/boardview.dart:569:22: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('../flutter/common/flutter/packages/flutter/lib/src/widgets/binding.dart').
WidgetsBinding.instance!.addPostFrameCallback((timeStamp) {
^
../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/flutter_datetime_picker-1.5.1/lib/flutter_datetime_picker.dart:311:32: Warning: Operand of null-aware operation '??' has type 'Color' which excludes null.
'Color' is from 'dart:ui'.
color: theme.backgroundColor ?? Colors.white,
^
../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/provider-5.0.0/lib/src/inherited_provider.dart:391:26: Warning: Operand of null-aware operation '!' has type 'SchedulerBinding' which excludes null.
'SchedulerBinding' is from 'package:flutter/src/scheduler/binding.dart' ('../flutter/common/flutter/packages/flutter/lib/src/scheduler/binding.dart').
SchedulerBinding.instance!.addPostFrameCallback((_) {
^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:421:47: Error: The getter 'title' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'title'.
TextStyle centerStyle = widget.textTheme?.title ??
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:422:32: Error: The getter 'title' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'title'.
appBarTheme.textTheme?.title ??
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:423:36: Error: The getter 'title' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'title'.
themeData.primaryTextTheme.title;
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:424:45: Error: The getter 'body1' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'body1'.
TextStyle sideStyle = widget.textTheme?.body1 ??
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:425:32: Error: The getter 'body1' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'body1'.
appBarTheme.textTheme?.body1 ??
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:426:36: Error: The getter 'body1' isn't defined for the class 'TextTheme'.
'TextTheme' is from 'package:flutter/src/material/text_theme.dart' ('../flutter/common/flutter/packages/flutter/lib/src/material/text_theme.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'body1'.
themeData.primaryTextTheme.body1;
^^^^^
../flutter/common/flutter/.pub-cache/git/GradientAppBar-37c4b1bea68eebaf29627cc696fcf8ed4701592e/lib/gradient_app_bar.dart:1177:9: Error: No named parameter with the name 'vsync'.
vsync: this,
^^^^^
../flutter/common/flutter/packages/flutter/lib/src/rendering/sliver_persistent_header.dart:500:3: Context: Found this candidate, but the arguments don't match.
FloatingHeaderSnapConfiguration({
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
../flutter/common/flutter/.pub-cache/hosted/pub.dartlang.org/platform-3.0.0/lib/src/interface/local_platform.dart:46:19: Error: Member not found: 'packageRoot'.
io.Platform.packageRoot; // ignore: deprecated_member_use
^^^^^^^^^^^
FAILURE: Build failed with an exception.

Where:
Script '/home/asmi/snap/flutter/common/flutter/packages/flutter_tools/gradle/flutter.gradle' line: 1156

What went wrong:
Execution failed for task ':app:compileFlutterBuildRelease'.

Process 'command '/home/asmi/snap/flutter/common/flutter/bin/flutter'' finished with non-zero exit value 1

Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

Get more help at https://help.gradle.org/

BUILD FAILED in 2m 45s
Running Gradle task 'assembleRelease'... 167.4s
Gradle task assembleRelease failed with exit code 1

[tripleFA]

Hi,
I managed to build the app by changing the gradient_app_bar dependency to new_gradient_app_bar.
Here is the diff file :

diff.txt