Fix : the type error in courseId page and extra breadcrumb separator

[amanbairagi30]

PR Fixes:

• 1 Type error in courses / [...coursesId] / page.tsx (which were marked as TODO : Fix These)
• 2 Extra BreadCrumb Separator

Before :

After :

Closes #385

Checklist before requesting a review

• [x] I have performed a self-review of my code
• [x] I assure there is no similar/duplicate pull request regarding same issue

[amanbairagi30]

Hey @hkirat , Could you review this PR ?