Double channel close in service-side db listener

[sanderpick]

textile_1  | panic: close of closed channel
textile_1  |
textile_1  | goroutine 44421195 [running]:
textile_1  | github.com/textileio/go-threads/db.(*listener).Close(0xc01e6ac990)
textile_1  | 	/go/pkg/mod/github.com/textileio/go-threads@v0.1.22-0.20200709194234-b75bad2b9536/db/listeners.go:145 +0x56
textile_1  | github.com/textileio/go-threads/api.(*Service).Listen(0xc015b56dd0, 0xc026fa0960, 0x200e220, 0xc01ad7d820, 0x0, 0x0)
textile_1  | 	/go/pkg/mod/github.com/textileio/go-threads@v0.1.22-0.20200709194234-b75bad2b9536/api/service.go:729 +0xa04
textile_1  | github.com/textileio/go-threads/api/pb._API_Listen_Handler(0x1854b80, 0xc015b56dd0, 0x2009780, 0xc01c43f820, 0x0, 0x0)
textile_1  | 	/go/pkg/mod/github.com/textileio/go-threads@v0.1.22-0.20200709194234-b75bad2b9536/api/pb/threads.pb.go:3250 +0x109
textile_1  | github.com/grpc-ecosystem/go-grpc-middleware/auth.StreamServerInterceptor.func1(0x1854b80, 0xc015b56dd0, 0x200a740, 0xc01068ab40, 0xc01c43ef80, 0x1d2a3a0, 0xc01c43efa0, 0xc01c43ef80)
textile_1  | 	/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.2.0/auth/auth.go:66 +0x148
textile_1  | github.com/grpc-ecosystem/go-grpc-middleware.ChainStreamServer.func1.1.1(0x1854b80, 0xc015b56dd0, 0x200a740, 0xc01068ab40, 0xc0227b6c68, 0x40cd58)
textile_1  | 	/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.2.0/chain.go:49 +0x5f
textile_1  | github.com/grpc-ecosystem/go-grpc-middleware.ChainStreamServer.func1(0x1854b80, 0xc015b56dd0, 0x200a740, 0xc01068ab40, 0xc01c43ef80, 0x1d2a3a0, 0x1fff9c0, 0xc01ceb0540)
textile_1  | 	/go/pkg/mod/github.com/grpc-ecosystem/go-grpc-middleware@v1.2.0/chain.go:58 +0xcf
textile_1  | google.golang.org/grpc.(*Server).processStreamingRPC(0xc0009428c0, 0x2013ec0, 0xc01d474240, 0xc014851a00, 0xc0161a31a0, 0x2d200a0, 0x0, 0x0, 0x0)
textile_1  | 	/go/pkg/mod/google.golang.org/grpc@v1.30.0/server.go:1425 +0x511
textile_1  | google.golang.org/grpc.(*Server).handleStream(0xc0009428c0, 0x2013ec0, 0xc01d474240, 0xc014851a00, 0x0)
textile_1  | 	/go/pkg/mod/google.golang.org/grpc@v1.30.0/server.go:1498 +0xc66
textile_1  | google.golang.org/grpc.(*Server).serveStreams.func1.2(0xc01d44af70, 0xc0009428c0, 0x2013ec0, 0xc01d474240, 0xc014851a00)
textile_1  | 	/go/pkg/mod/google.golang.org/grpc@v1.30.0/server.go:834 +0xa1
textile_1  | created by google.golang.org/grpc.(*Server).serveStreams.func1
textile_1  | 	/go/pkg/mod/google.golang.org/grpc@v1.30.0/server.go:832 +0x204