[web-devel] Yesod devel error: Yesod: panic! System/Plugins.hs:(84, 14)-(86, 29): Non-exhaustive patterns in lambda

Completely fresh install of yesod 0.8 I migrated my application successfully. It builds and works fine. But when trying yesod devel i get this error: yesod: panic! (the 'impossible' happened) (GHC version 7.0.2 for x86_64-unknown-linux): System/Plugins.hs:(84,14)-(86,29): Non-exhaustive patterns in lambda Also cabal gives me following warning on configure: Warning: This package indirectly depends on multiple versions of the same package. This is highly likely to cause a compile failure. package haskell-src-meta-0.3 requires syb-0.2.2 package aeson-0.3.2.4 requires syb-0.3 Not sure if its related to the error in any way, but it does not affect the build, and my executable works fine. Cheers, Vagif Verdi