traces inside of a try block are not flagged as error, even if error was thrown

[Domiii]

Problem

• Error thrown in try block does not get detected correctly.
• If error was thrown, first trace of finally block will be flagged as error trace (incorrectly).

Examples

• error4.js: error trace flagged incorrectly - should be todos (before todos.x) but is on = trace instead.
  • similar issue in error2.js -
  • using previousTraceInContext of PopImmediate does not work with try-catch cases

Solution

We are currently only resolving errors from PopImmediate in DataProvider.resolveErrorTraces. Currently, only traces that are PopImmediate and also !isTraceFunctionExit are error traces.

• add and instrument new TraceTypes:
  • TraceType.TryBlockExit
  • TraceType.Catch
  • TraceType.Finally
• fix up DataProvider.resolveErrorTraces
  • remove reliance on Trace.previousTrace (it seems to be inaccurate?)
    • use previousTrace = getPreviousInContext() instead?
  • remove getReturnTraceOfRealContext check (it's more complicated than that)
  • set error on previousTrace if...:

    • trace is Pop and !isTraceReturn(previousTrace) and !isTraceFunctionExit(previousTrace)

      • false-positive on try-finally, e.g. error-try-return-finally.js and error3.js

    • trace is TraceType.Catch

    • trace is TraceType.Finally and previousTrace is in try block and not TraceType.TryExit and !isTraceReturn(previousTrace) and !isTraceFunctionExit(previousTrace)

[MiccWan]

New algorithm works for most cases, except for nested try-finally. See __samplesInput__/nested-finally.js(false-positive in line 6 due to rule#3)