x/tools/gopls: panic in GetActiveReverseDeps

[muirdm]

On master (6536af71d98a5bb8f2cbd2f5e62afc2f6cc93dbb) just got this panic:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x166bbec]

goroutine 38327 [running]:
golang.org/x/tools/internal/lsp/cache.(*view).GetActiveReverseDeps(0xc000276900, 0x19813a0, 0xc03f1d1ce0, 0x2495068, 0xc0002c1c40, 0xc03e88b720, 0x0, 0xc03e850870)
	/Users/muir/projects/tools/internal/lsp/cache/gofile.go:114 +0x30c
golang.org/x/tools/internal/lsp/source.Diagnostics(0x19813a0, 0xc03f1d1ce0, 0x1991cc0, 0xc000276900, 0x2495068, 0xc0002c1c40, 0x0, 0x0, 0x0, 0x0, ...)
	/Users/muir/projects/tools/internal/lsp/source/diagnostics.go:87 +0x53a
golang.org/x/tools/internal/lsp.(*Server).diagnostics(0xc0002cc420, 0x1991cc0, 0xc000276900, 0xc04c768910, 0x46, 0x0, 0x0)
	/Users/muir/projects/tools/internal/lsp/diagnostics.go:30 +0x2d3
created by golang.org/x/tools/internal/lsp.(*Server).didChange
	/Users/muir/projects/tools/internal/lsp/text_synchronization.go:82 +0x366

I was in the middle of rebasing and resolving conflicts so a lot was in flux.

[gopherbot]

Thank you for filing a gopls issue! Please take a look at the Troubleshooting guide, and make sure that you have provided all of the relevant information here.

[gopherbot]

Change https://golang.org/cl/200300 mentions this issue: internal/lsp: return an error from {Narrowest,Widest}CheckPackageHandle