fix space after period

Author: mwilc0x

src/createStore.js

@@ -73,8 +73,8 @@ export default function createStore(reducer, initialState, enhancer) {
   function getState() {
     if (isDispatching) {
       throw new Error(
-        'You may not call store.getState() while the reducer is executing.' +
-        'The reducer has already received the state as an argument.' +
+        'You may not call store.getState() while the reducer is executing. ' +
+        'The reducer has already received the state as an argument. ' +
         'Pass it down from the top reducer instead of reading it from the store.'
       )
     }