Keybase Client on NixOS error code 218 - keybase version 2.6.0, nix-store (Nix) 2.1.1 nixos-18.09.1898.001b34abcb4

Error: ERROR CODE 218 - error unboxing chat message (transient): Key path not found in method chat.1.local.getThreadNonblock at new r (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:441228) at file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:441757 at u (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:441796) at _rpcClient.invoke.t (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:245338) at file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1758890 at e.t.Deferrals.e._call (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1649609) at file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1649760 at s (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1649389) at e.t.Deferrals.e._fulfill (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1649719) at s (file:///nix/store/pndhc9g4xnml81lzay9iph6yacdcxwil-keybase-gui-2.5.0-20180807164805.0fda758997/share/keybase/resources/app/desktop/dist/index.bundle.js:1:1648923)

Unable to open messages from sender on NixOS 18.09 keybase 2.6.0 desktop client.

Start by reproducing the chat error on NixOS 18.09 with Keybase 2.6.0 and inspect the reported app bundle path at /nix/store/.../share/keybase/resources/app/desktop/dist/index.bundle.js. Done means messages from the affected sender open without error code 218 or the missing key-path failure.

Written by the indexing model from the issue text.