fix read

src/read.luau

@@ -1,5 +1,42 @@
-local function read<T>(value: T | () -> T): T
+type function CastIntoValue(value: type)
-    return if type(value) == "function" then value() else value
+
+    local function get_return_for_fn(t: type)
+        local values = t:returns()
+        local head = values.head
+        local tail = values.tail
+
+        if head then
+            local first = head[1]
+            return first
+        elseif tail then
+            return tail
+        else
+            return types.singleton(nil)
+        end
+    end
+
+    if value.tag == "union" then
+        local components = value:components()
+        local possible_outcomes = {}
+
+        for _, v in components do
+            if v.tag == "function" then
+                table.insert(possible_outcomes, get_return_for_fn(v))
+            else
+                table.insert(possible_outcomes, v)
+            end
+        end
+
+        return types.unionof(unpack(possible_outcomes))
+    elseif value.tag == "function" then
+        return get_return_for_fn(value)
+    else
+        return value
+    end
+end
+
+local function read<T>(value: T): CastIntoValue<T>
+    return if type(value) == "function" then (value :: () -> T)() else value
 end
 
 return read