fix(#1841): fix unhandled missing index exception

Author: MSzalowski

CHANGELOG.md

@@ -17,6 +17,7 @@ changes.
 ### Fixed
 
 - Fix displaying DRep with doNotList property as string
+- Handle exception when no index is provided to /proposal/get endpoint [Issue 1841](https://github.com/IntersectMBO/govtool/issues/1841)
 
 ### Changed
 

govtool/backend/src/VVA/API/Types.hs

@@ -139,11 +139,14 @@ instance ToJSON GovActionId where
 instance FromHttpApiData GovActionId where
   parseUrlPiece t = case Text.splitOn "#" t of
       [hash, rest] -> do
-        index <- case readMaybe $ Text.unpack rest of
-          Just x -> pure x
-          _      -> Left (Text.tail rest <> " is not a number")
-        hexHash <- parseUrlPiece hash
-        Right $ GovActionId hexHash index
+        if Text.null rest
+          then Left "Missing index in hash#index format"
+          else do
+            index <- case readMaybe $ Text.unpack rest of
+              Just x -> pure x
+              _      -> Left (rest <> " is not a number")
+            hexHash <- parseUrlPiece hash
+            Right $ GovActionId hexHash index
       _ -> Left "Not a valid hash#index value"
 
 exampleGovActionId :: Text