Unfortunately, without pre-set user extended types configuration for events
and without --guess-eventtypes flag set we are allowed to rely only on manifest
information about types. Manifest can't give us a lot of information, but we
still need to be able to generate RPC binding. Arrays and structs are correctly
handled by the current code, but maps always rely on the fact that map's value
type is set. It's not true in the described case, so make the maps type convertor
handle this situation in a similar way how arrays are handled.
Without this commit the following panic occurs on attempt to generate RPC binding:
```
--- FAIL: TestAssistedRPCBindings/testdata/notifications (0.01s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x7f7c0e]
goroutine 190 [running]:
testing.tRunner.func1.2({0x109cb40, 0x1d58760})
/usr/local/go/src/testing/testing.go:1396 +0x24e
testing.tRunner.func1()
/usr/local/go/src/testing/testing.go:1399 +0x39f
panic({0x109cb40, 0x1d58760})
/usr/local/go/src/runtime/panic.go:884 +0x212
github.com/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding.extendedTypeToGo({0x22, {0x0, 0x0}, {0x0, 0x0}, 0x0, 0x0, {0x0, 0x0, 0x0}}, ...)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding/binding.go:515 +0x36e
github.com/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding.scTypeToGo({0xc000206d92?, 0xc000206d80?}, 0x22, 0xc0005d70e0)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding/binding.go:643 +0x138
github.com/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding.scTemplateToRPC({{0xc00049bb07, 0x7}, 0xc0004c89c0, {0x33, 0x22, 0x11, 0x0, 0xff, 0xee, 0xdd, ...}, ...}, ...)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding/binding.go:686 +0xbc4
github.com/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding.Generate({{0xc00049bb07, 0x7}, 0xc0004c89c0, {0x33, 0x22, 0x11, 0x0, 0xff, 0xee, 0xdd, ...}, ...})
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/pkg/smartcontract/rpcbinding/binding.go:421 +0x387
github.com/nspcc-dev/neo-go/cli/smartcontract.contractGenerateSomething(0xc00043e2c0, 0x137cd00)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/cli/smartcontract/generate.go:99 +0x855
github.com/nspcc-dev/neo-go/cli/smartcontract.contractGenerateRPCWrapper(0xc00043e2c0?)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/cli/smartcontract/generate.go:60 +0x25
github.com/urfave/cli.HandleAction({0x1048380?, 0x137c660?}, 0x13?)
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:524 +0x50
github.com/urfave/cli.Command.Run({{0x123539d, 0x13}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x12577ad, 0x2a}, {0x127ad35, ...}, ...}, ...)
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:173 +0x65b
github.com/urfave/cli.(*App).RunAsSubcommand(0xc0001f4000, 0xc00043e000)
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:405 +0x91b
github.com/urfave/cli.Command.startApp({{0x12281e1, 0x8}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1254d8a, 0x28}, {0x0, ...}, ...}, ...)
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:372 +0x6e7
github.com/urfave/cli.Command.Run({{0x12281e1, 0x8}, {0x0, 0x0}, {0x0, 0x0, 0x0}, {0x1254d8a, 0x28}, {0x0, ...}, ...}, ...)
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/command.go:102 +0x825
github.com/urfave/cli.(*App).Run(0xc00024e000, {0xc0004f6420, 0xb, 0xb})
/home/anna/go/pkg/mod/github.com/urfave/cli@v1.22.5/app.go:277 +0x8a7
github.com/nspcc-dev/neo-go/cli/smartcontract.TestAssistedRPCBindings.func1.1(0x9f8829?)
/home/anna/Documents/GitProjects/nspcc-dev/neo-go/cli/smartcontract/generate_test.go:395 +0x5fc
testing.tRunner(0xc0006824e0, 0xc0004a3680)
/usr/local/go/src/testing/testing.go:1446 +0x10b
created by testing.(*T).Run
/usr/local/go/src/testing/testing.go:1493 +0x35f
```
Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>
VM types are used in debugger, while smartcontract ones are used in
manifest. We can't save only one of them, because conversion in either
side is lossy:
1. VM has `Array` and `Struct` but smartcontract only has `Array`.
2. Smartcontract has `Hash160` etc, which are all `ByteString` or
`Buffer` in VM.
And to spice things a bit more, return type in debugger can be `Void`,
which corresponds to no real stackitem type (as it must exist).
