Errors saving decomposed production item when invalid entries in item cache

[isc-pbarton]

With production decomposition enabled, applying a change to a production item may give you an error alert:
File does not exist /git/repo/path/src/Package/ProductionName.cls
If you ignore the error alert, the item does save properly and is exported to the Git repo as expected.

The root cause can be found in the application error log:
sc = "0 "_$lb($lb(5001,"File does not exist - /git/repo/path/src/Package/ProductionName.cls",,,,,,,,$lb(,"JWHERR1",$lb("e^SetUncommitted+6^%Studio.SourceControl.Change.1^1","e^OnAfterSave+38^SourceControl.Git.Extension.1^1","e^OnProductionUpdate+22^EnsPortal.Template.prodConfigSCPage.1^1","d^CallProductionUpdateAndSaveToCl+28^EnsPortal.Template.prodConfigSCPage.1^1","e^SaveSettingsToServer+209^EnsPortal.ProductionConfig.1^1","e^InvokeClassMethod+131^%ZEN.Controller.1^1","x^InvokeClassMethod+131^%ZEN.Controller.1^1","e^InvokeClassMethod+2^%ZEN.Component.abstractPage.1^1","e^CSPEvent+10^%CSP.Broker.1^1","x^CSPEvent+10^%CSP.Broker.1^1","e^OnPage+3^%CSP.Broker.1^1","e^Page+9^%CSP.Broker.1^2","e^CSPDispatch+503^%SYS.cspServer^2","d^CSPDispatch+280^%SYS.cspServer^1","d^ProcessRequest+1^%CSP.Session.1^1","d^Request+692^%SYS.cspServer2^1","d^Request+25^%SYS.cspServer2^1","d^ProcessRequest+1^%CSP.Request.1^1","d^css+15^%SYS.cspServer2^1","d^Server+64^%SYS.SERVER^2","d^^^0"))))

The workaround is to run some commands in IRIS terminal to kill the nodes in the Git item cache corresponding to the undecomposed production:
kill ^SYS("SourceControl","Git","items","Package.ProductionName.cls")
kill ^SYS("SourceControl","Git","items","Package.ProductionName.CLS")

This needs a fix so that invalid entries in the item cache do not break saving other items.