Error: TSError: ⨯ Unable to compile TypeScript

Question

I am facing the problem:

My Project is built on Angular4 with typescript, e2e testing with protractor & karma.

Travis-ci has this error:

Answer 1

This is my solution for this issue: - Run this command

npm install -save-dev typescript@2.3.4

npm WARN code_gui@0.0.1 No repository field.
npm WARN code_gui@0.0.1 No license field.

+ typescript@2.3.4
updated 1 package and audited 657 packages in 2.539s
found 0 vulnerabilities