I followed instruction in https://preview.keenthemes.com/asp.net-core/metronic/docs/getting-started.
Here is the output that I get when running gulp --demo1. What did I do wrong? Thank you for your help.


D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools>gulp --demo1
Using gulp config file: "../../gulp.config.js"
[09:25:27] Using gulpfile D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\gulpfile.js
[09:25:27] Starting 'default'...
[09:25:27] Starting 'cleanTask'...
[09:25:27] Finished 'cleanTask' after 28 ms
[09:25:27] Starting 'buildBundleTask'...
[09:25:27] Finished 'buildBundleTask' after 72 ms
[09:25:27] Finished 'default' after 102 ms
Error in plugin "sass"
Message:
node_modules\prism-themes\themes\prismjs.bundle.css
Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'
D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:6365
throw error;
^

Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'
at Object.wrapException (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:2166:43)
at Object._failedAsCheck (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:3646:15)
at Rti._generalAsCheckImplementation [as _as] (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:3635:9)
at ArrayIterator.get$current (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:32948:50)
at Object.get$current$x (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:830:43)
at _SyncStarIterator.moveNext$0 (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:35808:41)
at Object.List_List$from (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:6379:49)
at Object.List_List$unmodifiable (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:6402:47)
at Object._parseImporter (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:27302:51)
at D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:27068:22 {
dartException: <ref *1> PluginError: TypeError: null: type 'JSNull' is not a subtype of type 'String'
at Object.wrapException (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:2166:43)
at Object._failedAsCheck (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:3646:15)
at Rti._generalAsCheckImplementation [as _as] (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:3635:9)
at ArrayIterator.get$current (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:32948:50)
at Object.get$current$x (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:830:43)
at _SyncStarIterator.moveNext$0 (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:35808:41)
at Object.List_List$from (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:6379:49)
at Object.List_List$unmodifiable (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:6402:47)
at Object._parseImporter (D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:27302:51)
at D:\COMPANIES\CV Software\Projects\iSpeak\SOLUTION\iSpeakCore\metronic_v8.2.3\metronic_asp.net-core_v8.2.3\Starterkit\_keenthemes\tools\node_modules\sass\sass.dart.js:27068:22 {
formatted: "Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'",
status: 3,
messageFormatted: '\x1B[4mnode_modules\\prism-themes\\themes\\prismjs.bundle.css\x1B[24m\n' +
"Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'",
messageOriginal: "TypeError: null: type 'JSNull' is not a subtype of type 'String'",
relativePath: 'node_modules\\prism-themes\\themes\\prismjs.bundle.css',
message: 'node_modules\\prism-themes\\themes\\prismjs.bundle.css\n' +
"Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'",
__safety: undefined,
_stack: undefined,
plugin: 'gulp-dart-sass',
showProperties: true,
showStack: false,
domainEmitter: PassThrough {
_events: {
close: [Function: onclose],
error: undefined,
prefinish: [Function: prefinish],
finish: [Function: onfinish],
drain: undefined,
data: [Function: ondata],
end: [
[Function: bound onceWrapper] { listener: [Function: onend] },
[Function: onend]
],
readable: undefined,
unpipe: [Function: remove]
},
_readableState: ReadableState {
highWaterMark: 16,
buffer: [],
bufferIndex: 0,
length: 0,
pipes: [
Sink {
_events: [Object],
_writableState: [WritableState],
_maxListeners: undefined,
_eventsCount: 4,
[Symbol(shapeMode)]: true,
[Symbol(kCapture)]: false
}
],
awaitDrainWriters: null,
[Symbol(kState)]: 194521357
},
_writableState: WritableState {
highWaterMark: 16,
length: 0,
corked: 0,
onwrite: [Function: bound onwrite],
writelen: 0,
bufferedIndex: 0,
pendingcb: 0,
[Symbol(kState)]: 17580301,
[Symbol(kBufferedValue)]: null
},
allowHalfOpen: true,
_maxListeners: 0,
_eventsCount: 6,
add: [Function: add],
isEmpty: [Function: isEmpty],
[Symbol(shapeMode)]: true,
[Symbol(kCapture)]: false,
[Symbol(kCallback)]: null
},
domainThrown: false,
'$cachedTrace': _StackTrace {
_exception: [Circular *1],
_trace: "Error: TypeError: null: type 'JSNull' is not a subtype of type 'String'\n" +
' at Object.wrapException (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:2166:43)\n' +
' at Object._failedAsCheck (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:3646:15)\n' +
' at Rti._generalAsCheckImplementation [as _as] (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:3635:9)\n' +
' at ArrayIterator.get$current (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:32948:50)\n' +
' at Object.get$current$x (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:830:43)\n' +
' at _SyncStarIterator.moveNext$0 (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:35808:41)\n' +
' at Object.List_List$from (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:6379:49)\n' +
' at Object.List_List$unmodifiable (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:6402:47)\n' +
' at Object._parseImporter (D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:27302:51)\n' +
' at D:\\COMPANIES\\CV Software\\Projects\\iSpeak\\SOLUTION\\iSpeakCore\\metronic_v8.2.3\\metronic_asp.net-core_v8.2.3\\Starterkit\\_keenthemes\\tools\\node_modules\\sass\\sass.dart.js:27068:22'
}
}
}

Node.js v20.11.1