When trying to run `flutter build web` i get "build web" is not currently supported.
I had previous errors where i was stuck with `Dart 2.5.0-dev.4.0.flutter-be66176534` and required 2.5.0 or higher, this has now been solved but i am unable to build my project.

```
flutter doctor -v
[√] Flutter (Channel stable, v1.9.1+hotfix.2, on Microsoft Windows [Version 10.0.18932.1000], locale en-GB)
    • Flutter version 1.9.1+hotfix.2 at C:\src\flutter
    • Framework revision 2d2a1ffec9 (8 days ago), 2019-09-06 18:39:49 -0700
    • Engine revision b863200c37
    • Dart version 2.5.0

[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at C:\Users\germa\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
    • All Android licenses accepted.

[!] Android Studio (version 3.4)
    • Android Studio at C:\Program Files\Android\Android Studio
    X Flutter plugin not installed; this adds Flutter specific functionality.
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[√] VS Code (version 1.38.1)
    • VS Code at C:\Users\germa\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.4.1

```

I have tried 

* re-installing dart
* re-installing flutter
* re-installing Visual Studio code
* copy file contents to a new web project (same error)

I couldn't find any information on what this is caused by and how to resolve it online

What can i do to resolve this error?