refactor: console.error message

Author: dannielss

packages/toolkit/src/createSlice.ts

@@ -268,7 +268,7 @@ export function createSlice<
     process.env.NODE_ENV === 'development'
   ) {
     if(options.initialState === undefined) {
-      console.error('initial state must be different of undefined')
+      console.error('You must provide an `initialState` value that is not `undefined`.  You may have misspelled `initialState`')
     }
   }
 

packages/toolkit/src/tests/createSlice.test.ts

@@ -53,7 +53,7 @@ describe('createSlice', () => {
         initialState: undefined,
       })
 
-      expect(getLog().log).toBe('initial state must be different of undefined')
+      expect(getLog().log).toBe('You must provide an `initialState` value that is not `undefined`.  You may have misspelled `initialState`')
     })
   })