Panic if actor is called during app startup

[waeljammal]

Describe the bug

We have a service that calls another every few seconds, if we restart the service along with dapr on the client being called and the other service makes a request the startup then we get this panic in the sdk.

[app] 6:44PM ERR panic: runtime error: invalid memory address or nil pointer dereference
[app] 6:31PM ERR goroutine 181 [running]: exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*api).CallActor(0x7a28688304055?, {0x1086b9790, 0x14000f02b70}, 0x6646430b?) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/api/grpc/daprinternal.go:285 +0x30 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/proto/internals/v1._ServiceInvocation_CallActor_Handler.func1({0x1086b9790, 0x14000f02b70}, {0x1083dbdc0?, 0x14001136e10}) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/proto/internals/v1/service_invocation_grpc.pb.go:156 +0x74 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*server).getMiddlewareOptions.(*grpcMetrics).UnaryServerInterceptor.func5({0x1086b9790, 0x14000f02b70}, {0x1083dbdc0, 0x14001136e10}, 0x1400057bbe0, 0x140004c9e00) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/diagnostics/grpc_monitoring.go:224 +0x6c exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*server).getMiddlewareOptions.ChainUnaryServer.func11.1({0x1086b9790?, 0x14000f02b70?}, {0x1083dbdc0?, 0x14001136e10?}) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.4.0/chain.go:48 +0x50 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*server).getMiddlewareOptions.GRPCTraceUnaryServerInterceptor.func3({0x1086b9790, 0x14000f02b10}, {0x1083dbdc0, 0x14001136e10}, 0x1400057bbe0, 0x14000b2f980) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/diagnostics/grpc_tracing.go:70 +0x1a4 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*server).getMiddlewareOptions.ChainUnaryServer.func11.1({0x1086b9790?, 0x14000f02b10?}, {0x1083dbdc0?, 0x14001136e10?}) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.4.0/chain.go:48 +0x50 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc/metadata.SetMetadataInContextUnary({0x1086b9790, 0x14000f02ab0}, {0x1083dbdc0, 0x14001136e10}, 0x140004c9e00?, 0x14000b2f9c0) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/api/grpc/metadata/metadata.go:46 +0xa0 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/api/grpc.(*server).getMiddlewareOptions.ChainUnaryServer.func11({0x1086b9790, 0x14000f02ab0}, {0x1083dbdc0, 0x14001136e10}, 0x1400057bbe0, 0x102976278?) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.4.0/chain.go:53 +0x128 exec=dapr level=info
[app] 6:31PM ERR github.com/dapr/dapr/pkg/proto/internals/v1._ServiceInvocation_CallActor_Handler({0x1085f4260?, 0x14001710c80}, {0x1086b9790, 0x14000f02ab0}, 0x140012b2880, 0x1400123eab0) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/work/dapr/dapr/pkg/proto/internals/v1/service_invocation_grpc.pb.go:158 +0x12c exec=dapr level=info
[app] 6:31PM ERR google.golang.org/grpc.(*Server).processUnaryRPC(0x1400124c000, {0x1086b9790, 0x14000f02a20}, {0x1086d9940, 0x14000503a00}, 0x14000f6a000, 0x1400123edb0, 0x10b8834a0, 0x0) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/google.golang.org/grpc@v1.60.1/server.go:1372 +0xb8c exec=dapr level=info
[app] 6:31PM ERR google.golang.org/grpc.(*Server).handleStream(0x1400124c000, {0x1086d9940, 0x14000503a00}, 0x14000f6a000) exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/google.golang.org/grpc@v1.60.1/server.go:1783 +0xc4c exec=dapr level=info
[app] 6:31PM ERR google.golang.org/grpc.(*Server).serveStreams.func2.1() exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/google.golang.org/grpc@v1.60.1/server.go:1016 +0x5c exec=dapr level=info
[app] 6:31PM ERR created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 177 exec=dapr level=info
[app] 6:31PM ERR 	/Users/runner/go/pkg/mod/google.golang.org/grpc@v1.60.1/server.go:1027 +0x138 exec=dapr level=info

To Reproduce

Create a service using the sdk and register an actor and call Start() on the service, Create a second service that invokes the actor at a high frequency, lets say 2 - 3 seconds now restart the service if the timing is right the sdk should panic.

Expected behavior

I expected that the caller would just get an error back because the service is not ready yet but instead the service crashes.