Followed build instructions correctly but get a lot of errors:
`
[at-loader] Checking finished with 75 errors
[22:16:27] [webpack] Hash: 8eddc28930e55a15c836
Version: webpack 2.3.2
Time: 11616ms
Asset Size Chunks Chunk Names
popup.js 182 kB 0 [emitted] popup
content.js 769 bytes 1 [emitted] content
background.js 1.01 kB 2 [emitted] background
./../styles/bundle.css 163 kB 0 [emitted] popup
popup.js.map 1.9 MB 0 [emitted] popup
./../styles/bundle.css.map 239 kB 0 [emitted] popup
content.js.map 7.3 kB 1 [emitted] content
background.js.map 8.03 kB 2 [emitted] background
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:350:48
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:351:52
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:352:34
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:353:34
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:354:34
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:355:61
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:356:60
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:357:65
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:357:97
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:358:60
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:359:58
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:360:59
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:361:58
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:362:61
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:362:117
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:363:42
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:365:81
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:366:78
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:367:76
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:368:73
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:464:59
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:465:59
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:467:48
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:468:69
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:472:40
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:474:48
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:494:55
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:495:45
TS2304: Cannot find name 'PropertyKey'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:627:20
TS2304: Cannot find name 'PromiseConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1280:36
TS2339: Property 'for' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1284:43
TS2339: Property 'hasInstance' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1288:50
TS2339: Property 'isConcatSpreadable' does not exist on type 'SymbolConstruc
tor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1296:38
TS2339: Property 'keyFor' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1300:37
TS2339: Property 'match' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1304:39
TS2339: Property 'replace' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1308:38
TS2339: Property 'search' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1312:39
TS2339: Property 'species' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1316:37
TS2339: Property 'split' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1320:43
TS2339: Property 'toPrimitive' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1324:43
TS2339: Property 'toStringTag' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:1328:43
TS2339: Property 'unscopables' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2059:36
TS2339: Property 'for' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2063:43
TS2339: Property 'hasInstance' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2067:50
TS2339: Property 'isConcatSpreadable' does not exist on type 'SymbolConstruc
tor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2075:38
TS2339: Property 'keyFor' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2079:37
TS2339: Property 'match' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2083:39
TS2339: Property 'replace' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2087:38
TS2339: Property 'search' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2091:39
TS2339: Property 'species' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2095:37
TS2339: Property 'split' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2099:43
TS2339: Property 'toPrimitive' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2103:43
TS2339: Property 'toStringTag' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/core-js/index.d.ts:2107:43
TS2339: Property 'unscopables' does not exist on type 'SymbolConstructor'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:11:13
TS2300: Duplicate identifier 'fetch'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:13:14
TS2300: Duplicate identifier 'HeadersInit'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:14:15
TS2300: Duplicate identifier 'Headers'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:31:14
TS2300: Duplicate identifier 'BodyInit'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:41:14
TS2300: Duplicate identifier 'RequestInfo'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:42:15
TS2300: Duplicate identifier 'Request'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:61:11
TS2300: Duplicate identifier 'Request'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:84:15
TS2300: Duplicate identifier 'Response'.
ERROR in [at-loader] ./node_modules/@types/whatwg-fetch/index.d.ts:102:11
TS2300: Duplicate identifier 'Response'.
ERROR in [at-loader] ./node_modules/@types/whatwg-streams/index.d.ts:25:15
TS2300: Duplicate identifier 'ReadableStream'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:11168:11
TS2300: Duplicate identifier 'Headers'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:11177:13
TS2300: Duplicate identifier 'Headers'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13544:11
TS2300: Duplicate identifier 'ReadableStream'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13550:13
TS2300: Duplicate identifier 'ReadableStream'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13566:11
TS2300: Duplicate identifier 'Request'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13583:13
TS2300: Duplicate identifier 'Request'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13588:11
TS2300: Duplicate identifier 'Response'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:13599:13
TS2300: Duplicate identifier 'Response'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:19116:18
TS2300: Duplicate identifier 'fetch'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:19121:6
TS2300: Duplicate identifier 'BodyInit'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:19142:6
TS2300: Duplicate identifier 'HeadersInit'.
ERROR in [at-loader] ./node_modules/typescript/lib/lib.d.ts:19152:6
TS2300: Duplicate identifier 'RequestInfo'.
[22:16:27] Finished 'build-chromeExt' after 12 s
[22:16:27] Starting 'generate-chrome-dev'...
[22:16:27] Finished 'generate-chrome-dev' after 24 µs`