Assertion failure when compiling NimYAML
Out of interest, I tried to compile NimYAML with this. NimYAML commit is [6bb110b185c27a4e00e7c486de27626cf1418c62](https://github.com/flyx/NimYAML/commit/6bb110b185c27a4e00e7c486de27626cf1418c62). This is what I got:

```
Traceback (most recent call last)
nlvm.nim(117)            nlvm
nlvm.nim(108)            handleCmdLine
nlvm.nim(53)             mainCommand
nlvm.nim(29)             commandLL
modules.nim(250)         compileProject
modules.nim(195)         compileModule
passes.nim(203)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(488)             myProcess
sem.nim(460)             semStmtAndGenerateGenerics
semstmts.nim(1562)       semStmt
semexprs.nim(873)        semExprNoType
semexprs.nim(2417)       semExpr
importer.nim(176)        evalImport
importer.nim(165)        myImportModule
modules.nim(208)         importModule
modules.nim(195)         compileModule
passes.nim(203)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(488)             myProcess
sem.nim(460)             semStmtAndGenerateGenerics
semstmts.nim(1562)       semStmt
semexprs.nim(873)        semExprNoType
semexprs.nim(2417)       semExpr
importer.nim(176)        evalImport
importer.nim(165)        myImportModule
modules.nim(208)         importModule
modules.nim(195)         compileModule
passes.nim(203)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(488)             myProcess
(28 calls omitted) ...
modules.nim(208)         importModule
modules.nim(195)         compileModule
passes.nim(203)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(488)             myProcess
sem.nim(460)             semStmtAndGenerateGenerics
semstmts.nim(1562)       semStmt
semexprs.nim(873)        semExprNoType
semexprs.nim(2417)       semExpr
importer.nim(176)        evalImport
importer.nim(165)        myImportModule
modules.nim(208)         importModule
modules.nim(195)         compileModule
passes.nim(203)          processModule
passes.nim(137)          processTopLevelStmt
sem.nim(488)             myProcess
sem.nim(460)             semStmtAndGenerateGenerics
semstmts.nim(1562)       semStmt
semexprs.nim(873)        semExprNoType
semexprs.nim(2410)       semExpr
semstmts.nim(1340)       semProc
semstmts.nim(1274)       semProcAux
semexprs.nim(1479)       semProcBody
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2327)       semExpr
semexprs.nim(766)        semIndirectOp
semexprs.nim(2340)       semExpr
semexprs.nim(1321)       semArrayAccess
semexprs.nim(1297)       semSubscript
semcall.nim(419)         explicitGenericInstantiation
semcall.nim(400)         explicitGenericSym
seminst.nim(317)         generateInstance
seminst.nim(155)         instantiateBody
semexprs.nim(1479)       semProcBody
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2390)       semExpr
semexprs.nim(1435)       semAsgn
semexprs.nim(42)         semExprWithType
semexprs.nim(2325)       semExpr
semexprs.nim(857)        semDirectOp
semexprs.nim(848)        afterCallActions
semmagic.nim(170)        magicsAfterOverloadResolution
semmagic.nim(42)         semArrGet
semexprs.nim(1297)       semSubscript
semcall.nim(419)         explicitGenericInstantiation
semcall.nim(400)         explicitGenericSym
seminst.nim(317)         generateInstance
seminst.nim(155)         instantiateBody
semexprs.nim(1479)       semProcBody
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2403)       semExpr
semstmts.nim(215)        semCase
semstmts.nim(116)        semExprBranchScope
semstmts.nim(107)        semExprBranch
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2403)       semExpr
semstmts.nim(215)        semCase
semstmts.nim(116)        semExprBranchScope
semstmts.nim(107)        semExprBranch
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2390)       semExpr
semexprs.nim(1435)       semAsgn
semexprs.nim(42)         semExprWithType
semexprs.nim(2325)       semExpr
semexprs.nim(857)        semDirectOp
semexprs.nim(848)        afterCallActions
semmagic.nim(170)        magicsAfterOverloadResolution
semmagic.nim(42)         semArrGet
semexprs.nim(1297)       semSubscript
semcall.nim(419)         explicitGenericInstantiation
semcall.nim(400)         explicitGenericSym
seminst.nim(317)         generateInstance
seminst.nim(155)         instantiateBody
semexprs.nim(1479)       semProcBody
semexprs.nim(2392)       semExpr
semstmts.nim(1516)       semStmtList
semexprs.nim(2390)       semExpr
semexprs.nim(1447)       semAsgn
sem.nim(75)              fitNode
semcall.nim(298)         indexTypesMatch
sigmatch.nim(1498)       paramTypesMatch
sigmatch.nim(1374)       paramTypesMatchAux
sigmatch.nim(932)        typeRel
sigmatch.nim(537)        procTypeRel
types.nim(1415)          compatibleEffects
types.nim(1393)          compatibleEffectsAux
types.nim(1386)          safeInheritanceDiff
types.nim(1015)          inheritanceDiff
system.nim(3416)         failedAssertImpl
system.nim(3408)         raiseAssert
system.nim(2547)         sysFatal
Error: unhandled exception: a.kind == tyObject  [AssertionError]
```

Not sure if this is an nlvm bug or due to outdated Nim version (NimYAML devel currently does not compile against Nim stable, but with different errors).
