import { createStore, combineReducers, compose } from 'redux';
import { VERSION, CONSTRAINT } from './actions';
import semver from './semver';

const initialState = {
    version: { version: '', semver: null },
    constraint: { constraint: '', semver: null },
};

const version = (state = { version: '', semver: null }, action) => {
    if (action.type === VERSION) {
        const cleaned = semver.clean(action.version);

        return {
            ...state,
            version: action.version,
            semver: semver.coerce(cleaned),
        };
    }

    return state;
};

const constraint = (state = { constraint: '', semver: null }, action) => {
    if (action.type === CONSTRAINT) {
        const cleaned = semver.cleanRange(action.constraint);

        return {
            ...state,
            constraint: action.constraint,
            semver: semver.coerceRange(cleaned),
        };
    }

    return state;
};

const reducers = combineReducers({
    version,
    constraint,
});

const enhancers = [];

if (process.env.NODE_ENV !== 'production' && window.__REDUX_DEVTOOLS_EXTENSION__) {
    enhancers.push(window.__REDUX_DEVTOOLS_EXTENSION__())
}

export default createStore(
    reducers,
    initialState,
    compose(...enhancers),
);

import { createStore, combineReducers } from 'redux';
import { VERSION, CONSTRAINT } from './actions';
import semver from './semver';

const initialState = {
    version: { version: '', semver: null },
    constraint: { constraint: '', semver: null },
};

const version = (state = { version: '', semver: null }, action) => {
    if (action.type === VERSION) {
        const cleaned = semver.clean(action.version);

        return {
            ...state,
            version: action.version,
            semver: semver.coerce(cleaned),
        };
    }

    return state;
};

const constraint = (state = { constraint: '', semver: null }, action) => {
    if (action.type === CONSTRAINT) {
        const cleaned = semver.cleanRange(action.constraint);

        return {
            ...state,
            constraint: action.constraint,
            semver: semver.coerceRange(cleaned),
        };
    }

    return state;
};

const reducers = combineReducers({
    version,
    constraint,
});

export default createStore(
    reducers,
    initialState,
    process.env.NODE_ENV !== 'production' &&
        window.__REDUX_DEVTOOLS_EXTENSION__ &&
        window.__REDUX_DEVTOOLS_EXTENSION__(),
);

--- 
+++ 
@@ -1,4 +1,4 @@
-import { createStore, combineReducers, compose } from 'redux';
+import { createStore, combineReducers } from 'redux';
 import { VERSION, CONSTRAINT } from './actions';
 import semver from './semver';
 
@@ -40,14 +40,10 @@
     constraint,
 });
 
-const enhancers = [];
-
-if (process.env.NODE_ENV !== 'production' && window.__REDUX_DEVTOOLS_EXTENSION__) {
-    enhancers.push(window.__REDUX_DEVTOOLS_EXTENSION__())
-}
-
 export default createStore(
     reducers,
     initialState,
-    compose(...enhancers),
+    process.env.NODE_ENV !== 'production' &&
+        window.__REDUX_DEVTOOLS_EXTENSION__ &&
+        window.__REDUX_DEVTOOLS_EXTENSION__(),
 );
fix: Fix an error about Redux enhancers
