vspd error while voting

[feeleep75]

Latest version of dcrd, dcrwallet and vspd. On client side latest version of decredition.

Here is the log file when client tries to vote:

{"timestamp":1647768231,"tickethash":"488c0daf24f781787d44e68ee24418a6ec62ed537d1f6947ca68c0f038a5f825","votechoices":{"autorevocations":"yes","changesubsidysplit":"yes","explicitverupgrades":"yes","reverttreasurypolicy":"yes"},"tspendpolicy":{},"treasurypolicy":{}}
2022-03-20 09:23:51.208 [ERR] API: panic recovered: assignment to entry in nil map

/usr/lib/go-1.17/src/runtime/map_faststr.go:204 (0x41494e)
        mapassign_faststr: panic(plainError("assignment to entry in nil map"))
/.../vspd/webapi/setvotechoices.go:123 (0x960bbe)
        setVoteChoices: ticket.VoteChoices[newAgenda] = newChoice
/.../go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/context.go:168 (0x967daa)
        (*Context).Next: c.handlers[c.index](c)
/.../vspd/webapi/recovery.go:53 (0x967d94)
        Recovery.func1: c.Next()
/.../go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/context.go:168 (0x944950)
        (*Context).Next: c.handlers[c.index](c)
/.../go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/gin.go:555 (0x9445b8)
        (*Engine).handleHTTPRequest: c.Next()
/.../go/pkg/mod/github.com/gin-gonic/gin@v1.7.7/gin.go:511 (0x9440f1)
        (*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/usr/lib/go-1.17/src/net/http/server.go:2879 (0x6d6aba)
        serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/usr/lib/go-1.17/src/net/http/server.go:1930 (0x6d2167)
        (*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/usr/lib/go-1.17/src/runtime/asm_amd64.s:1581 (0x4661c0)
        goexit: BYTE    $0x90   // NOP

[Jamie Holdstock]

Thanks for the report. This bug was introduced in #323, the penultimate commit before the release happened.