Pack script fixes

pack.ps1

@@ -1,9 +1,17 @@
 dotnet pack "src\Discord.Net.Core\Discord.Net.Core.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.Rest\Discord.Net.Rest.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.WebSocket\Discord.Net.WebSocket.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.Rpc\Discord.Net.Rpc.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.Commands\Discord.Net.Commands.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.Providers.WS4Net\Discord.Net.Providers.WS4Net.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 dotnet pack "src\Discord.Net.Providers.UdpClient\Discord.Net.Providers.UdpClient.csproj" -c "Release" -o "../../artifacts" --no-build /p:BuildNumber="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
 
-call nuget pack src\Discord.Net\Discord.Net.nuspec -OutputDirectory "artifacts" -properties build="$Env:BUILD"
+nuget pack src\Discord.Net\Discord.Net.nuspec -OutputDirectory "artifacts" -properties build="$Env:BUILD"
+if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }