Two different panics during SELECT percentile

[mark-rushakoff]

From commit 9824585:

When I run the query SELECT percentile(value) FROM "random_measurement_0" WHERE time > now() - 12h GROUP BY time(5m), the server panics. Granted, percentile takes two arguments and this shouldn't work, but it shouldn't panic either.

panic: runtime error: index out of range

goroutine 2781 [running]:
github.com/influxdb/influxdb/influxql.InitializeReduceFunc(0xc2086b7680, 0x1, 0x0, 0x0)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/functions.go:110 +0x62b
github.com/influxdb/influxdb/influxql.(*MapReduceJob).Execute(0xc208721880, 0xc20845da40, 0xc208228700)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:89 +0x274
github.com/influxdb/influxdb/influxql.(*Executor).execute(0xc208788f80, 0xc20845da40)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:774 +0xba
created by github.com/influxdb/influxdb/influxql.(*Executor).Execute
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:753 +0x5a

Then when I run a more proper query like SELECT percentile(value, 75) FROM "random_measurement_0" WHERE time > now() - 12h GROUP BY time(5m), I get a different panic:

panic: interface conversion: interface is nil, not []interface {}

goroutine 4402 [running]:
github.com/influxdb/influxdb/influxql.func·016(0xc2081c4fc0, 0xc, 0xc, 0x0, 0x0)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/functions.go:548 +0x107
github.com/influxdb/influxdb/influxql.(*MapReduceJob).processAggregate(0xc208789730, 0xc2088827b0, 0xc20865b9e0, 0xc2087f5000, 0x91, 0x91, 0x0, 0x0)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:632 +0x33d
github.com/influxdb/influxdb/influxql.(*MapReduceJob).Execute(0xc208789730, 0xc20877c9c0, 0xc208074000)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:167 +0x8bf
github.com/influxdb/influxdb/influxql.(*Executor).execute(0xc208698c40, 0xc20877c9c0)
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:774 +0xba
created by github.com/influxdb/influxdb/influxql.(*Executor).Execute
        /Users/mr/go/src/github.com/influxdb/influxdb/influxql/engine.go:753 +0x5a