Internal error "not unused" adding else branch to if in macro

[gradha]

I have other else branches and if working fine, so something peculiar must be going about this little change. To reproduce:

$ git clone https://github.com/gradha/nimrod-objective-c-bridge.git
$ cd nimrod-objective-c-bridge
$ git checkout compiler_error_unused 
$ cd examples/ex_greeter/
$ nimrod objc ex_greeter.nim
objcbridge/core.nim(124, 8) Error: internal error: not unused
Traceback (most recent call last)
nimrod.nim(87)           nimrod
nimrod.nim(55)           handleCmdLine
main.nim(321)            mainCommand
main.nim(73)             commandCompileToC
modules.nim(193)         compileProject
modules.nim(151)         compileModule
passes.nim(192)          processModule
passes.nim(136)          processTopLevelStmt
sem.nim(379)             myProcess
sem.nim(353)             semStmtAndGenerateGenerics
semstmts.nim(1290)       semStmt
semexprs.nim(819)        semExprNoType
semexprs.nim(2027)       semExpr
importer.nim(169)        evalImport
importer.nim(161)        myImportModule
modules.nim(164)         importModule
modules.nim(151)         compileModule
passes.nim(192)          processModule
passes.nim(136)          processTopLevelStmt
sem.nim(379)             myProcess
sem.nim(353)             semStmtAndGenerateGenerics
semstmts.nim(1290)       semStmt
semexprs.nim(819)        semExprNoType
semexprs.nim(2027)       semExpr
importer.nim(169)        evalImport
importer.nim(161)        myImportModule
modules.nim(164)         importModule
modules.nim(151)         compileModule
passes.nim(192)          processModule
passes.nim(136)          processTopLevelStmt
sem.nim(379)             myProcess
sem.nim(353)             semStmtAndGenerateGenerics
semstmts.nim(1290)       semStmt
semexprs.nim(819)        semExprNoType
semexprs.nim(1908)       semExpr
sem.nim(287)             semMacroExpr
vm.nim(1174)             evalMacroCall
vmgen.nim(1480)          genProc
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1307)          gen
vmgen.nim(255)           genWhile
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1304)          gen
vmgen.nim(384)           genCase
vmgen.nim(1321)          gen
vmgen.nim(210)           gen
vmgen.nim(1303)          gen
vmgen.nim(305)           genIf
vmgen.nim(1281)          gen
vmgen.nim(766)           genMagic
vmgen.nim(353)           unused
msgs.nim(817)            internalError
msgs.nim(794)            liMessage
msgs.nim(710)            handleError