type 'Null' is not a subtype of type 'String'

or smilar error

type 'String' is not a subtype of type 'int' of 'value'

for i have design map 

so the type will be Map<string,int> when add string value to this map , error will show

so declare the 

Uncaught SyntaxError: Cannot use import statement outside a module (at index.js:2:1)

1.vue:1  Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "". Strict MIME type checking is enforced for module scripts per HTML spec.