Fix fsc task to check for nulls, https://github.com/fsharp/fsharp/issues/628 (#1638)
Fix fsc task to check for nulls, https://github.com/fsharp/fsharp/issues/628 (#1638)


brettfo/visualfsharp,alfonsogarciacaro/FSharp.Compiler.Service,dsyme/fsharp,cloudRoutine/FSharp.Compiler.Service,syeerzy/visualfsharp,brettfo/visualfsharp,brettfo/visualfsharp,brettfo/visualfsharp,dsyme/fsharp,0x53A/FSharp.Compiler.Service,dsyme/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,syeerzy/visualfsharp,rojepp/FSharp.Compiler.Service,ncave/FSharp.Compiler.Service,dsyme/fsharp,rojepp/FSharp.Compiler.Service,0x53A/FSharp.Compiler.Service,syeerzy/visualfsharp,syeerzy/visualfsharp,dsyme/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,forki/FSharp.Compiler.Service,fsharp/fsharp,fsharp/fsharp,fsharp/fsharp,ncave/FSharp.Compiler.Service,dsyme/fsharp,rojepp/FSharp.Compiler.Service,0x53A/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,dsyme/FSharp.Compiler.Service,forki/FSharp.Compiler.Service,forki/FSharp.Compiler.Service,syeerzy/visualfsharp,brettfo/visualfsharp,dsyme/fsharp,dsyme/fsharp,brettfo/visualfsharp,ncave/FSharp.Compiler.Service,sergey-tihon/FSharp.Compiler.Service,Jand42/FSharp.Compiler.Service,alfonsogarciacaro/FSharp.Compiler.Service,syeerzy/visualfsharp,Jand42/FSharp.Compiler.Service,dsyme/fsharp,alfonsogarciacaro/FSharp.Compiler.Service,Jand42/FSharp.Compiler.Service