fixes for some errors

Author: Julian Currie

lib/widget/cheetah_button.dart

@@ -3,12 +3,12 @@ import 'package:flutter/material.dart';
 class CheetahButton extends StatelessWidget {
   final String text;
   final Function onPressed;
-  final Color? color;
-  final Color? textColor;
+  final Color color;
+  final Color textColor;
 
   CheetahButton({
-    required this.text,
-    required this.onPressed,
+    @required this.text,
+    @required this.onPressed,
     this.color,
     this.textColor,
   });
@@ -32,7 +32,7 @@ class CheetahButton extends StatelessWidget {
             color: textColor ?? Colors.white,
           ),
         ),
-        onPressed: onPressed(),
+        onPressed: onPressed,
       ),
     );
   }

lib/widget/cheetah_input.dart

@@ -22,7 +22,7 @@ class CheetahInput extends StatelessWidget {
       validator: (String value) {
         return value.isEmpty ? '$labelText is required' : null;
       },
-      onSaved: onSaved(),
+      onSaved: onSaved,
     );
   }
 }