x/tools/gopls: panic in KnownPackages

[muirdm]

I'm seeing the below panic sometimes.

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x16a2073]

goroutine 110092 [running]:
golang.org/x/tools/internal/lsp/cache.(*snapshot).KnownPackages(0xc0733632c0, 0x19b32c0, 0xc089a94c90, 0x18, 0xa0d9148a631f54a5, 0xc04688d360)
	/Users/muir/projects/tools/internal/lsp/cache/snapshot.go:147 +0x393
golang.org/x/tools/internal/lsp/source.(*IdentifierInfo).implementations(0xc07b0c9b00, 0x19b32c0, 0xc089a94c90, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/Users/muir/projects/tools/internal/lsp/source/implementation.go:113 +0x12b
golang.org/x/tools/internal/lsp/source.(*IdentifierInfo).Implementation(0xc07b0c9b00, 0x19b32c0, 0xc089a94c90, 0xc00037e000, 0x56f09f0, 0xc00066a080, 0x402c000000000000, 0x4014000000000000)
	/Users/muir/projects/tools/internal/lsp/source/implementation.go:23 +0x5d
golang.org/x/tools/internal/lsp.(*Server).implementation(0xc000287080, 0x19b32c0, 0xc089a94c90, 0xc089a94d50, 0xc089a94d50, 0x0, 0x0, 0x0, 0xc07b217600)
	/Users/muir/projects/tools/internal/lsp/implementation.go:26 +0x1a4
golang.org/x/tools/internal/lsp.(*Server).Implementation(0xc000287080, 0x19b32c0, 0xc089a94c90, 0xc089a94d50, 0xc089a94d50, 0x0, 0x0, 0xc07dd49bf8, 0x1046f6c)
	/Users/muir/projects/tools/internal/lsp/server.go:185 +0x4d
golang.org/x/tools/internal/lsp/protocol.serverHandler.Deliver(0x19cc840, 0xc000287080, 0x19b32c0, 0xc089a94c90, 0xc042edf340, 0xc089a94c00, 0xc07b2301e0)
	/Users/muir/projects/tools/internal/lsp/protocol/tsserver.go:201 +0x4b0e
golang.org/x/tools/internal/jsonrpc2.(*Conn).Run.func1(0xc07a1c4a80, 0xc042edf340, 0xc0002870e0, 0x19b32c0, 0xc089a94c90, 0x0, 0x0, 0xc01bc1dda0)
	/Users/muir/projects/tools/internal/jsonrpc2/jsonrpc2.go:370 +0x170
created by golang.org/x/tools/internal/jsonrpc2.(*Conn).Run
	/Users/muir/projects/tools/internal/jsonrpc2/jsonrpc2.go:354 +0x877

[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/207346 mentions this issue: internal/lsp: fix panic when logging errors in snapshot.KnownPackages