Panic when running on windows

[AvyChanna]

When not inside a module, GOMOD is set to NUL on windows (instead of /dev/null). This

// From `go help environment` ->
GOMOD
                The absolute path to the go.mod of the main module.
                If module-aware mode is enabled, but there is no go.mod, GOMOD will be
                os.DevNull ("/dev/null" on Unix-like systems, "NUL" on Windows).
                If module-aware mode is disabled, GOMOD will be the empty string.

gomodguard/processor.go

Line 268 in 112c09d

if goEnv["GOMOD"] == "/dev/null" {

Here's the stacktrace when running with golangci-lint

[runner] Panic stack trace: goroutine 1 [running]:
runtime/debug.Stack()
	C:/Program Files/Go/src/runtime/debug/stack.go:24 +0x5e
github.com/golangci/golangci-lint/pkg/lint.(*Runner).runLinterSafe.func1()
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/lint/runner.go:147 +0x279
panic({0x153b0e0?, 0x220de90?})
	C:/Program Files/Go/src/runtime/panic.go:770 +0x132
github.com/ryancurrah/gomodguard.(*Processor).SetBlockedModules(0xc001e1a438)
	C:/Users/username/go/pkg/mod/github.com/ryancurrah/gomodguard@v1.3.2/processor.go:144 +0x52
github.com/ryancurrah/gomodguard.NewProcessor(0xc000ad0540)
	C:/Users/username/go/pkg/mod/github.com/ryancurrah/gomodguard@v1.3.2/processor.go:66 +0x165
github.com/golangci/golangci-lint/pkg/golinters/gomodguard.New.func1(0xc000738ae0)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/golinters/gomodguard/gomodguard.go:68 +0x3e
github.com/golangci/golangci-lint/pkg/goanalysis.(*Linter).preRun(0xc000ada540, 0xc000738ae0)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/goanalysis/linter.go:157 +0xd7
github.com/golangci/golangci-lint/pkg/goanalysis.MetaLinter.Run({{0xc000818200, 0x3c, 0x40}, 0xc0005013e0}, {0x70d880?, 0xc001351f80?}, 0xc000738ae0)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/goanalysis/metalinter.go:26 +0x85
github.com/golangci/golangci-lint/pkg/lint.(*Runner).runLinterSafe(0xc00121f750?, {0x1970d30?, 0xc000bb1180?}, 0xc000738ae0, 0xc000524380)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/lint/runner.go:152 +0xb5
github.com/golangci/golangci-lint/pkg/lint.(*Runner).Run.func1()
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/lint/runner.go:120 +0x5b
github.com/golangci/golangci-lint/pkg/timeutils.(*Stopwatch).TrackStage(0xc0013105a0, {0x173db39, 0x15}, 0xc00121f958)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/timeutils/stopwatch.go:111 +0x44
github.com/golangci/golangci-lint/pkg/lint.(*Runner).Run(0xc00130e9c0, {0x1970d30, 0xc000bb1180}, {0xc00012a6e0, 0x1, 0xc0008ce980?})
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/lint/runner.go:119 +0x276
github.com/golangci/golangci-lint/pkg/commands.(*runCommand).runAnalysis(0xc0008c2d80, {0x1970d30, 0xc000bb1180}, {0xc0008ce980, 0x1, 0x4})
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/commands/run.go:390 +0x1f1
github.com/golangci/golangci-lint/pkg/commands.(*runCommand).runAndPrint(0xc0008c2d80, {0x1970d30, 0xc000bb1180}, {0xc0008ce980, 0x1, 0x4})
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/commands/run.go:347 +0x285
github.com/golangci/golangci-lint/pkg/commands.(*runCommand).execute(0xc0008c2d80, 0xc000779b18?, {0xc0008ce980, 0x1, 0x4})
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/commands/run.go:253 +0x1f3
github.com/spf13/cobra.(*Command).execute(0xc000884908, {0xc0008ce940, 0x4, 0x4})
	C:/Users/username/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:944 +0x867
github.com/spf13/cobra.(*Command).ExecuteC(0xc000884308)
	C:/Users/username/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3a5
github.com/spf13/cobra.(*Command).Execute(...)
	C:/Users/username/go/pkg/mod/github.com/spf13/cobra@v1.7.0/command.go:992
github.com/golangci/golangci-lint/pkg/commands.(*rootCommand).Execute(0xc0008c8930)
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/commands/root.go:83 +0x3d
github.com/golangci/golangci-lint/pkg/commands.Execute({{0x19607d8, 0x8}, {0x19e0baf, 0x7}, {0xc0005cf260, 0x52}, {0x16baf39, 0x9}})
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/pkg/commands/root.go:17 +0x5a
main.main()
	C:/Users/username/go/pkg/mod/github.com/golangci/golangci-lint@v1.58.2/cmd/golangci-lint/main.go:24 +0xc5

[runner] Can't run linter goanalysis_metalinter: panic occurred: runtime error: invalid memory address or nil pointer dereference