Couldn't match type ‘a’ with ‘Int’ / ‘a’ is untouchable / inside the constraints ()

Sadly I'm a Haskell newbie, so this won't be a very good bug report, but I am working on a codebase and I triggered a GHC bug (at least according to GHC itself).

Building json-log-viewer-0.0.1...
Preprocessing executable 'json-log-viewer' for json-log-viewer-0.0.1...
[3 of 3] Compiling Main             ( src/Main.hs, dist/build/json-log-viewer/json-log-viewer-tmp/Main.o )

src/Main.hs:316:41:
    Couldn't match type ‘a’ with ‘Int’
      ‘a’ is untouchable
        inside the constraints ()
        bound by the inferred type of refreshMessages :: IO ()
        at src/Main.hs:(300,7)-(324,48)ghc: panic! (the 'impossible' happened)
  (GHC version 7.10.1 for x86_64-apple-darwin):
	No skolem info: a_al2w[sk]

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

I saved the state of the code in a git branch and put it here: https://github.com/radix/json-log-viewer/tree/ghc-bug

I'll also attach my list of cabal dependencies installed. The only tricky one is that I'm working off of an unreleased version of vty-ui, at this revision: https://github.com/jtdaugherty/vty-ui/commit/c3a0c4b660119a4d5862a6f549a98739a3fc5fa7

I also don't know if the program is "valid" -- I'm in the middle of a refactor, and it's a big cluttered program that I know is very poorly written. Sorry about that. I would not usually report a bug in such a situation but the compiler implored me to, so I am.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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