index out of range error for request

[bwaz]

The parser panics when the "request" parameter is not set to a value.
http://localhost:8181/v1/data?request

2017/01/16 09:28:36 http: panic serving 127.0.0.1:42608: runtime error: index out of range
goroutine 45 [running]:
net/http.(*conn).serve.func1(0xc4201b0380)
/usr/local/go/src/net/http/server.go:1491 +0x12a
panic(0x85a3e0, 0xc42000e110)
/usr/local/go/src/runtime/panic.go:458 +0x243
github.com/open-policy-agent/opa/server.parseRequest(0xc4202be310, 0x1, 0x1, 0x7, 0xc4201b5aa8, 0xf0, 0xc4202de960, 0x0)
/go/src/github.com/open-policy-agent/opa/server/server.go:1074 +0x80a
github.com/open-policy-agent/opa/server.(*Server).v1DataGet(0xc42000ae60, 0xadfce0, 0xc4202b43a0, 0xc4202de960)
/go/src/github.com/open-policy-agent/opa/server/server.go:471 +0x229
github.com/open-policy-agent/opa/server.(*Server).(github.com/open-policy-agent/opa/server.v1DataGet)-fm(0xadfce0, 0xc4202b43a0, 0xc4202de960)
/go/src/github.com/open-policy-agent/opa/server/server.go:310 +0x48
net/http.HandlerFunc.ServeHTTP(0xc420184590, 0xadfce0, 0xc4202b43a0, 0xc4202de960)
/usr/local/go/src/net/http/server.go:1726 +0x44
github.com/open-policy-agent/opa/vendor/github.com/gorilla/mux.(*Router).ServeHTTP(0xc42000aeb0, 0xadfce0, 0xc4202b43a0, 0xc4202de960)
/go/src/github.com/open-policy-agent/opa/vendor/github.com/gorilla/mux/mux.go:114 +0x10d
github.com/open-policy-agent/opa/runtime.(*LoggingHandler).ServeHTTP(0xc420185e50, 0xae05e0, 0xc4201bc1a0, 0xc4202de780)
/go/src/github.com/open-policy-agent/opa/runtime/logging.go:30 +0xf8
net/http.serverHandler.ServeHTTP(0xc42001b700, 0xae05e0, 0xc4201bc1a0, 0xc4202de780)
/usr/local/go/src/net/http/server.go:2202 +0x7d
net/http.(*conn).serve(0xc4201b0380, 0xae0da0, 0xc4202b8280)
/usr/local/go/src/net/http/server.go:1579 +0x4b7
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:2293 +0x44d
2017/01/16 09:28:36 http: panic serving 127.0.0.1:42610: runtime error: index out of range
goroutine 46 [running]:
net/http.(*conn).serve.func1(0xc4201b0480)
/usr/local/go/src/net/http/server.go:1491 +0x12a
panic(0x85a3e0, 0xc42000e110)

[tsandall]

Oops! parseRequest should check for empty strings. Should be an easy fix.