Possible race in persistent storage.

[ericsnowcurrently]

See: https://dev.azure.com/ms/vscode-python/_build/results?buildId=53561&view=logs

Error 2019-12-09 22:06:53: Failed to activate a workspace, Class name = p, completed in 18331ms, Arg 1: <Uri:d:\a\1\s\src\testMultiRootWkspc\smokeTests>, Return Value: undefined TypeError: Cannot read property 'fileHash' of undefined
    at C.updateCachedInterpreterInformation (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1186987)
    at C.getInterpreterDetails (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1185338)
    at C.activate (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:64400)
    at async Promise.all (index 0)
    at p.activateWorkspace (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:60843)
Error 2019-12-09 22:06:53: sendStartupTelemetry() failed. TypeError: Cannot read property 'fileHash' of undefined
    at C.updateCachedInterpreterInformation (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1186987)
    at C.getInterpreterDetails (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1185338)
    at C.activate (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:64400)
    at async Promise.all (index 0)
    at p.activateWorkspace (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:60843)
Error 2019-12-09 22:06:53: Failure during activation. TypeError: Cannot read property 'fileHash' of undefined
    at C.updateCachedInterpreterInformation (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1186987)
    at C.getInterpreterDetails (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:75:1185338)
    at C.activate (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:64400)
    at async Promise.all (index 0)
    at p.activateWorkspace (d:\a\1\s\tmp\ext\smokeTestExtensionsFolder\out\client\extension.js:68:60843)
TypeError: Cannot read property 'fileHash' of undefined
TypeError: Cannot read property 'fileHash' of undefined

From what I can tell in InterpreterService.getInterpreterCache(), the returned state.value will always be set (never undefined). So in updateCachedInterpreterInformation() the lookup on state.value.fileHash should never faile like it did in the above logs. The only explanation I can think of is that there is either a race or a silenced error in the persistent state code (or the underlying Memento implementation).

See:

• src/client/interpreter/interpreterService.ts
• src/client/common/persistentState.ts