Looking to install this on my mac on the Flutter dev channel, but getting a pub get error:

Because dartx >=0.2.0 <0.4.0 depends on path >=1.6.4 <1.7.0 and every version of flutter_test from sdk depends on path 1.7.0, dartx >=0.2.0 <0.4.0 is incompatible with flutter_test from sdk.
So, because neucalcu depends on both flutter_test any from sdk and dartx ^0.3.0, version solving failed.

...

SLVR:   ! dartx ^0.3.0 is satisfied by dartx ^0.3.0
SLVR:   ! which is caused by "neucalcu depends on dartx ^0.3.0"
SLVR:   ! thus: version solving failed
SLVR: Version solving took 0:00:03.039692 seconds.
    | Tried 1 solutions.
FINE: Resolving dependencies finished (3.1s).
ERR : Because no versions of dartx match >0.3.0 <0.4.0 and dartx 0.3.0 depends on path >=1.6.4 <1.7.0, dartx ^0.3.0 requires path >=1.6.4 <1.7.0.
    | And because every version of flutter_test from sdk depends on path 1.7.0, dartx ^0.3.0 is incompatible with flutter_test from sdk.
    | So, because neucalcu depends on both flutter_test any from sdk and dartx ^0.3.0, version solving failed.
FINE: Exception type: SolveFailure
FINE: package:pub/src/solver/version_solver.dart 312:5   VersionSolver._resolveConflict
    | package:pub/src/solver/version_solver.dart 133:27  VersionSolver._propagate
    | package:pub/src/solver/version_solver.dart 97:11   VersionSolver.solve.<fn>
    | ===== asynchronous gap ===========================
    | dart:async                                         Future.catchError
    | package:pub/src/utils.dart 113:52                  captureErrors.wrappedCallback
    | package:stack_trace                                Chain.capture
    | package:pub/src/utils.dart 126:11                  captureErrors

    | package:pub/src/command_runner.dart 193:13         PubCommandRunner.runCommand

---- End log transcript ----
pub get failed (1; ---- End log transcript ----)
exit code 1

Any thoughts please? I am a beginner in Flutter but have a working development environment and have created quite a few test flutter apps.

P.S. This calc project seems to cause vscode to show all packages with red underlines, incl import 'package:flutter/material.dart'; e.g. a similar issue is discussed at https://github.com/flutter/flutter/issues/19384 in other projects. However my other flutter projects are ok. Flutter doctor is OK.