API Data retrieval bug

[lizlove]

VM3162:1 GET http://localhost:5000/api/sortingresults net::ERR_EMPTY_RESPONSE (anonymous) @ VM3162:1 (anonymous) @ d33084d91d6e14629496.js:78 dispatchXhrRequest @ xhr.js:155 xhrAdapter @ xhr.js:16 dispatchRequest @ dispatchRequest.js:49 Promise.then (async) request @ Axios.js:55 Axios. @ Axios.js:65 wrap @ bind.js:11 _callee$ @ actionCreators.js:43 tryCatch @ runtime.js:45 invoke @ runtime.js:264 prototype. @ runtime.js:98 asyncGeneratorStep @ asyncToGenerator.js:3 _next @ asyncToGenerator.js:25 (anonymous) @ asyncToGenerator.js:32 (anonymous) @ asyncToGenerator.js:21 createFetchAPI @ actionCreators.js:43 (anonymous) @ actionCreators.js:230 (anonymous) @ index.js:8 (anonymous) @ redux.js:476 _callee$ @ index.js:48 tryCatch @ runtime.js:45 invoke @ runtime.js:264 prototype. @ runtime.js:98 asyncGeneratorStep @ asyncToGenerator.js:3 _next @ asyncToGenerator.js:25 (anonymous) @ asyncToGenerator.js:32 (anonymous) @ asyncToGenerator.js:21 componentDidMount @ index.js:57 commitLifeCycles @ react-dom.development.js:22052 commitLayoutEffects @ react-dom.development.js:25295 callCallback @ react-dom.development.js:337 sentryWrapped @ index.js:3848 invokeGuardedCallbackDev @ react-dom.development.js:386 invokeGuardedCallback @ react-dom.development.js:439 commitRootImpl @ react-dom.development.js:25033 unstable_runWithPriority @ scheduler.development.js:823 runWithPriority$2 @ react-dom.development.js:12210 commitRoot @ react-dom.development.js:24882 finishSyncRender @ react-dom.development.js:24277 performSyncWorkOnRoot @ react-dom.development.js:24257 scheduleUpdateOnFiber @ react-dom.development.js:23647 updateContainer @ react-dom.development.js:27056 (anonymous) @ react-dom.development.js:27473 unbatchedUpdates @ react-dom.development.js:24385 legacyRenderSubtreeIntoContainer @ react-dom.development.js:27472 render @ react-dom.development.js:27557 render @ index.js:26 ./src/index.js @ index.js:34 webpack_require @ bootstrap:785 fn @ bootstrap:150 0 @ utils.js:35 webpack_require @ bootstrap:785 checkDeferredModules @ bootstrap:45 webpackJsonpCallback @ bootstrap:32 (anonymous) @ main.chunk.js:1 Show 26 more frames VM3162:1 GET http://localhost:5000/api/studysets net::ERR_CONNECTION_REFUSED (anonymous) @ VM3162:1 (anonymous) @ d33084d91d6e14629496.js:78 dispatchXhrRequest @ xhr.js:155 xhrAdapter @ xhr.js:16 dispatchRequest @ dispatchRequest.js:49 Promise.then (async) request @ Axios.js:55 Axios. @ Axios.js:65 wrap @ bind.js:11 _callee$ @ actionCreators.js:43 tryCatch @ runtime.js:45 invoke @ runtime.js:264 prototype. @ runtime.js:98 asyncGeneratorStep @ asyncToGenerator.js:3 _next @ asyncToGenerator.js:25 (anonymous) @ asyncToGenerator.js:32 (anonymous) @ asyncToGenerator.js:21 createFetchAPI @ actionCreators.js:43 (anonymous) @ actionCreators.js:208 (anonymous) @ index.js:8 (anonymous) @ redux.js:476 _callee$ @ index.js:52 tryCatch @ runtime.js:45 invoke @ runtime.js:264 prototype. @ runtime.js:98 asyncGeneratorStep @ asyncToGenerator.js:3 _next @ asyncToGenerator.js:25 (anonymous) @ asyncToGenerator.js:32 (anonymous) @ asyncToGenerator.js:21 componentDidMount @ index.js:57 commitLifeCycles @ react-dom.development.js:22052 commitLayoutEffects @ react-dom.development.js:25295 callCallback @ react-dom.development.js:337 sentryWrapped @ index.js:3848 invokeGuardedCallbackDev @ react-dom.development.js:386 invokeGuardedCallback @ react-dom.development.js:439 commitRootImpl @ react-dom.development.js:25033 unstable_runWithPriority @ scheduler.development.js:823 runWithPriority$2 @ react-dom.development.js:12210 commitRoot @ react-dom.development.js:24882 finishSyncRender @ react-dom.development.js:24277 performSyncWorkOnRoot @ react-dom.development.js:24257 scheduleUpdateOnFiber @ react-dom.development.js:23647 updateContainer @ react-dom.development.js:27056 (anonymous) @ react-dom.development.js:27473 unbatchedUpdates @ react-dom.development.js:24385 legacyRenderSubtreeIntoContainer @ react-dom.development.js:27472 render @ react-dom.development.js:27557 render @ index.js:26 ./src/index.js @ index.js:34 webpack_require @ bootstrap:785 fn @ bootstrap:150 0 @ utils.js:35 webpack_require @ bootstrap:785 checkDeferredModules @ bootstrap:45 webpackJsonpCallback @ bootstrap:32 (anonymous) @ main.chunk.js:1 Show 26 more frames redux.js:463 Uncaught (in promise) Error: Given action "RECEIVE_SORTING_RESULTS", reducer "sortingResults" returned undefined. To ignore an action, you must explicitly return the previous state. If you want this reducer to hold no value, you can return null instead of undefined. at combination (redux.js:463) at dispatch (redux.js:212) at middleware.js:36 at index.js:11 at dispatch (redux.js:638) at actionCreators.js:232 combination @ redux.js:463 dispatch @ redux.js:212 (anonymous) @ middleware.js:36 (anonymous) @ index.js:11 dispatch @ redux.js:638 (anonymous) @ actionCreators.js:232 Promise.then (async) (anonymous) @ actionCreators.js:233 (anonymous) @ index.js:8 (anonymous) @ redux.js:476 _callee$ @ index.js:48 tryCatch @ runtime.js:45 invoke @ runtime.js:264 prototype. @ runtime.js:98 asyncGeneratorStep @ asyncToGenerator.js:3 _next @ asyncToGenerator.js:25 (anonymous) @ asyncToGenerator.js:32 (anonymous) @ asyncToGenerator.js:21 componentDidMount @ index.js:57 commitLifeCycles @ react-dom.development.js:22052 commitLayoutEffects @ react-dom.development.js:25295 callCallback @ react-dom.development.js:337 sentryWrapped @ index.js:3848 invokeGuardedCallbackDev @ react-dom.development.js:386 invokeGuardedCallback @ react-dom.development.js:439 commitRootImpl @ react-dom.development.js:25033 unstable_runWithPriority @ scheduler.development.js:823 runWithPriority$2 @ react-dom.development.js:12210 commitRoot @ react-dom.development.js:24882 finishSyncRender @ react-dom.development.js:24277 performSyncWorkOnRoot @ react-dom.development.js:24257 scheduleUpdateOnFiber @ react-dom.development.js:23647 updateContainer @ react-dom.development.js:27056 (anonymous) @ react-dom.development.js:27473 unbatchedUpdates @ react-dom.development.js:24385 legacyRenderSubtreeIntoContainer @ react-dom.development.js:27472 render @ react-dom.development.js:27557 render @ index.js:26 ./src/index.js @ index.js:34 webpack_require @ bootstrap:785 fn @ bootstrap:150 0 @ utils.js:35 webpack_require @ bootstrap:785 checkDeferredModules @ bootstrap:45 webpackJsonpCallback @ bootstrap:32 (anonymous) @ main.chunk.js:1 Show 15 more frames redux.js:463 Uncaught (in promise) Error: Given action "RECEIVE_STUDY_SETS", reducer "studySets" returned undefined. To ignore an action, you must explicitly return the previous state. If you want this reducer to hold no value, you can return null instead of undefined.