Check llvm::Expected before use

[dvrogozh]

Fixes: #77

That's effectively reuse of the same approach already used in IGC elsewhere:

intel-graphics-compiler/IGC/Compiler/Optimizer/BuiltInFuncImport.cpp

Line 378 in 952d4d1

if (llvm::Error EC = ModuleOrErr.takeError())

[paigeale]

Hello Dmitry,
Look like this pull request is already implemented with your change a0a1599.

Closing down

Thanks,
Alex Paige

[dvrogozh]

Yes, it is addressed. Sorry for allowing dangling issue to hang.