chore(ghc): disable almost all warnings, even under flag pedantic

package.yaml

@@ -245,10 +245,8 @@ default-extensions:
   - StandaloneKindSignatures
   - NoStarIsType
 ghc-options:
-  - -Wall
+  - -w
   - -Wmissing-home-modules
-  - -Wredundant-constraints
-  - -Widentities
   - -Wincomplete-uni-patterns
   - -fno-warn-type-defaults
   - -fno-warn-unrecognised-pragmas
@@ -259,7 +257,6 @@ ghc-options:
 when:
   - condition: flag(pedantic)
     ghc-options:      
-      - -Werror
       - -fwarn-tabs
   - condition: flag(dev)
     then:

src/Handler/Course/List.hs

@@ -294,6 +294,7 @@ makeCourseTable colChoices psValidator' = do
 
 getCourseListR :: Handler Html
 getCourseListR = do
+  varNotUsed <- return "just a test to see whether warnings are disabled properly"
   muid <- maybeAuthId
   let colonnade = widgetColonnade $ mconcat
         [ colCourse -- colCourseDescr