x/tools/gopls: Hover bug reported by telemetry

[adonovan]

This stack DaKTNg PE4R3g was reported by telemetry:

source.hover:188 is

bug.Reportf("no metadata for %s", uri)

gopls/bug
golang.org/x/tools/gopls/internal/bug.report:35
golang.org/x/tools/gopls/internal/bug.Errorf:2
golang.org/x/tools/gopls/internal/lsp/source.hover:188
golang.org/x/tools/gopls/internal/lsp/source.Hover:4
golang.org/x/tools/gopls/internal/lsp.(*Server).hover:18
golang.org/x/tools/gopls/internal/lsp.(*Server).Hover:1
golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch:300
golang.org/x/tools/gopls/internal/lsp/protocol.ServerHandler.func1:5
golang.org/x/tools/gopls/internal/lsp/lsprpc.handshaker.func1:52
golang.org/x/tools/internal/jsonrpc2.MustReplyHandler.func1:2
golang.org/x/tools/internal/jsonrpc2.AsyncHandler.func1.2:3
runtime.goexit:0

golang.org/x/tools/gopls@v0.14.1 go1.19.1 darwin/amd64 (2)

Reported using golang.org/x/tools/gopls/internal/telemetry/cmd/stacks.

[gopherbot]

Change https://go.dev/cl/549117 mentions this issue: gopls/internal/lsp/source: hovering over broken packages is not an error