fix: ensure build stops if prepare_vscode fails

[Iheb-AG]

Add error handling for preparation step in build script

[daiyam]

It already taken care with set -ex.

Which error does it fail to catch?

[Iheb-AG]

You're right that set -e covers most failures. However, during local testing, I found that if prepare_vscode.sh is sourced, certain shell environments allowed build.sh to continue despite internal errors. This explicit check ensures the build strictly halts the moment preparation fails, preventing the system from wasting resources on a broken build process.

[daiyam]

certain shell environments

Can you be more explicit?

[Iheb-AG]

I am using fish as my shell. When running the build, I noticed that if an error happens inside the sourced prepare_vscode.sh, the main build.sh doesn't always stop—it just keeps going.