how i slove this error

[Bhuvan90902002]

C:\b\s\w\ir\x\w\sdk\pkg\dartdev\bin\dartdev.dart 13:5 main
This is an unexpected error. The full log and other details are collected in:

C:\Users\DELL 5470\AppData\Local\Pub\Cache\log\pub_log.txt

Consider creating an issue on https://github.com/dart-lang/pub/issues/new
and attaching the relevant parts of that log file.
PS D:\vishaliya\vishwaliya_flutter> flutter pub get
Resolving dependencies...
Downloading packages...
Null check operator used on a null value
package:pub/src/source/hosted.dart 760:33 HostedSource._getAdvisories.readAdvisoriesFromCache
===== asynchronous gap ===========================
package:pub/src/source/hosted.dart 778:12 HostedSource._getAdvisories
===== asynchronous gap ===========================
package:pub/src/source/hosted.dart 1066:24 HostedSource.getAdvisoriesForPackageVersion
===== asynchronous gap ===========================
package:pub/src/solver/report.dart 414:26 SolveReport._reportPackage
===== asynchronous gap ===========================
package:pub/src/solver/report.dart 218:18 SolveReport._reportChanges
===== asynchronous gap ===========================
package:pub/src/solver/report.dart 73:21 SolveReport.show
===== asynchronous gap ===========================
package:pub/src/entrypoint.dart 568:5 Entrypoint.acquireDependencies
===== asynchronous gap ===========================
package:pub/src/command/get.dart 77:5 GetCommand.runProtected
===== asynchronous gap ===========================
package:pub/src/command.dart 196:7 PubCommand.run
===== asynchronous gap ===========================
package:args/command_runner.dart 212:13 CommandRunner.runCommand
===== asynchronous gap ===========================
package:dartdev/dartdev.dart 232:18 DartdevRunner.runCommand
===== asynchronous gap ===========================
package:dartdev/dartdev.dart 46:16 runDartdev
===== asynchronous gap ===========================
C:\b\s\w\ir\x\w\sdk\pkg\dartdev\bin\dartdev.dart 13:5 main
This is an unexpected error. The full log and other details are collected in:

C:\Users\DELL 5470\AppData\Local\Pub\Cache\log\pub_log.txt

Consider creating an issue on https://github.com/dart-lang/pub/issues/new

[sigurdm]

Duplicate of #4269

This is fixed in 3.4.4 and 3.5.0