glide tree error "panic: runtime error: invalid memory address or nil pointer dereference"

[gubei]

When using glide tree to print dependency tree , I found a error.

| |-- github.com/go-sql-driver/mysql (/home/gubei/gocode/src/github.com/xiaohuanggua/virgin/vendor/github.com/go-sql-driver/mysql)
| | |-- appengine/cloudsql ()
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x20 pc=0x4e2233]

goroutine 1 [running]:
panic(0x945080, 0xc82000e170)
/usr/local/Cellar/go/1.6/libexec/src/runtime/panic.go:464 +0x3e6
github.com/Masterminds/glide/dependency.srcDir(0x0, 0x0, 0xc81ffea1e0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/dependency/resolver.go:927 +0x33
github.com/Masterminds/glide/dependency.IsSrcDir(0x0, 0x0, 0xc81ffea1e0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/dependency/resolver.go:923 +0x2b
github.com/Masterminds/glide/tree.walkDeps.func1(0x0, 0x0, 0x0, 0x0, 0x7fa5ea9a1608, 0xc8202bc3f0, 0x0, 0x0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/tree/tree.go:48 +0x92
path/filepath.Walk(0x0, 0x0, 0xc8201ccac8, 0x0, 0x0)
/usr/local/Cellar/go/1.6/libexec/src/path/filepath/path.go:394 +0x

my os system is fedora linux .

thank you for helping.

[abhin4v]

I get the same error on OSX 10.10.5:

$ ~/.gocode/src/github.com/Masterminds/glide/glide tree
[... some output ...]
goroutine 1 [running]:
panic(0x5723a0, 0xc8200120e0)
        /usr/local/Cellar/go/1.6/libexec/src/runtime/panic.go:464 +0x3e6
github.com/Masterminds/glide/dependency.srcDir(0x0, 0x0, 0xc81ffe5553)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/dependency/resolver.go:1035 +0x33
github.com/Masterminds/glide/dependency.IsSrcDir(0x0, 0x0, 0xc8201060b9)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/dependency/resolver.go:1031 +0x2b
github.com/Masterminds/glide/tree.walkDeps.func1(0x0, 0x0, 0x0, 0x0, 0xd18888, 0xc820355590, 0x0, 0x0)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:48 +0x95
path/filepath.Walk(0x0, 0x0, 0xc8201cc3a8, 0x0, 0x0)
        /usr/local/Cellar/go/1.6/libexec/src/path/filepath/path.go:394 +0xa5
github.com/Masterminds/glide/tree.walkDeps(0xc82018cc30, 0x0, 0x0, 0xc8202ace21, 0x12, 0x0, 0x0, 0x0)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:93 +0xc0
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0x0, 0x0, 0xc8202ace21, 0x12, 0x7, 0x0, 0xc820355410)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:19 +0x77
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc820356000, 0x6d, 0xc820290d81, 0x1f, 0x6, 0x0, 0xc820354120)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc82028e5b0, 0x6d, 0xc8201332f1, 0x1f, 0x5, 0x0, 0xc820290720)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc820010d70, 0x4d, 0xc8201d7e41, 0x32, 0x4, 0x0, 0xc820132750)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc820010820, 0x4b, 0xc82026ac41, 0x30, 0x3, 0x0, 0xc8201b1020)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc820270ae0, 0x51, 0xc820189681, 0x36, 0x2, 0x0, 0xc820257620)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/tree.Display(0xc82018cc30, 0xc8200100a4, 0x46, 0xc82019815b, 0x2b, 0x1, 0xc820182f00, 0xc8201b0660)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/tree/tree.go:40 +0x846
github.com/Masterminds/glide/action.Tree(0xc8200100a4, 0x46, 0xc82018e500)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/action/tree.go:32 +0x385
main.commands.func14(0xc82018e500)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/glide.go:619 +0x31
github.com/Masterminds/glide/vendor/github.com/codegangsta/cli.Command.Run(0x6186e8, 0x4, 0x0, 0x0, 0x0, 0x0, 0x0, 0x6c0ac0, 0x37, 0x0, ...)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/vendor/github.com/codegangsta/cli/command.go:179 +0x1399
github.com/Masterminds/glide/vendor/github.com/codegangsta/cli.(*App).Run(0xc8200a5080, 0xc82000a220, 0x2, 0x2, 0x0, 0x0)
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/vendor/github.com/codegangsta/cli/app.go:196 +0x137c
main.main()
        /Users/abhinav/.gocode/src/github.com/Masterminds/glide/glide.go:122 +0x750

[mattfarina]

Fixed by #544