Catch failed download of miniupnpc (#821)

* Catch failed download of miniupnpc

* Reverting to Python 3.7 due to miniupnpc

.github/workflows/build-windows-installer.yml

@@ -65,9 +65,9 @@ jobs:
           destination-file: .\electron-react\win_code_sign_cert.p12
 
       - uses: actions/setup-python@v2
-        name: Install Python 3.8
+        name: Install Python 3.7
         with:
-          python-version: "3.8"
+          python-version: "3.7"
 
       - name: Build Windows installer with build_scripts\build_windows.ps1
         env:

build_scripts/build_windows.ps1

@@ -10,7 +10,15 @@ Write-Output "curl miniupnpc"
 Write-Output "   ---"
 Invoke-WebRequest -Uri "https://download.chia.net/simple/miniupnpc/miniupnpc-2.1-cp37-cp37m-win_amd64.whl" -OutFile "miniupnpc-2.1-cp37-cp37m-win_amd64.whl"
 Write-Output "Using win_amd64 python 3.7 wheel from https://github.com/miniupnp/miniupnp/pull/475 (2.2.0-RC1)"
-Set-Location -Path - -PassThru
+If ($LastExitCode -gt 0){
+    Throw "Failed to download miniupnpc!"
+}
+else
+{
+    Set-Location -Path - -PassThru
+    Write-Output "miniupnpc download successful."
+}
+
 
 Write-Output "   ---"
 Write-Output "Create venv - python3.7 or 3.8 is required in PATH"