More accurate error messages when failing to set properties (#315)

src/Instances/applyInstanceProps.lua

@@ -19,6 +19,7 @@ local External = require(Package.External)
 local cleanup = require(Package.Utility.cleanup)
 local xtypeof = require(Package.Utility.xtypeof)
 local logError = require(Package.Logging.logError)
+local parseError = require(Package.Logging.parseError)
 local Observer = require(Package.State.Observer)
 local peek = require(Package.State.peek)
 
@@ -31,7 +32,9 @@ local function testPropertyAssignable(instance: Instance, property: string)
 end
 
 local function setProperty(instance: Instance, property: string, value: any)
-	if not pcall(setProperty_unsafe, instance, property, value) then
+	local success, err = xpcall(setProperty_unsafe, parseError, instance, property, value)
+
+	if not success then
 		if not pcall(testPropertyAssignable, instance, property) then
 			if instance == nil then
 				-- reference has been lost
@@ -45,7 +48,12 @@ local function setProperty(instance: Instance, property: string, value: any)
 			-- this typically implies the wrong type was received
 			local givenType = typeof(value)
 			local expectedType = typeof((instance :: any)[property])
-			logError("invalidPropertyType", nil, instance.ClassName, property, expectedType, givenType)
+
+			if givenType == expectedType then
+				logError("propertySetError", err)
+			else
+				logError("invalidPropertyType", nil, instance.ClassName, property, expectedType, givenType)
+			end
 		end
 	end
 end

src/Logging/messages.lua

@@ -42,6 +42,7 @@ return {
 	mistypedSpringSpeed = "The speed of a spring must be a number. (got a %s)",
 	mistypedTweenInfo = "The tween info of a tween must be a TweenInfo. (got a %s)",
 	noTaskScheduler = "Fusion is not connected to an external task scheduler.",
+	propertySetError = "Error setting property: ERROR_MESSAGE",
 	springTypeMismatch = "The type '%s' doesn't match the spring's type '%s'.",
 	stateGetWasRemoved = "`StateObject:get()` has been replaced by `use()` and `peek()` - see discussion #217 on GitHub.",
 	strictReadError = "'%s' is not a valid member of '%s'.",