Ionic Showing Blank Page and error on build

When we run ionic serve -l its showing blank page. and when run build command its show error:

Error: Debug Failure. 
    at typeToString (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:28777:22)
    at reportRelationError (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:34714:34)
    at isRelatedTo (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:34860:21)
    at checkTypeRelatedTo (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:34697:26)
    at checkTypeAssignableTo (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:34398:20)
    at checkAssignmentOperator (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:42645:25)
    at checkBinaryLikeExpression (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:42598:21)
    at checkBinaryExpression (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:42467:20)
    at checkExpressionWorker (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:42980:28)
    at checkExpression (/Users/hispiritstechnologies/apps/beblee/node_modules/typescript/lib/typescript.js:42898:42)

its was working fine before