Remove extra if and else chain

Checklist

• make -j4 test (UNIX), or vcbuild test nosign (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

vm

Description of change

• Remove extra if and else chain for better readability
• Extract new runInThisContext and runInContext function so no code duplication and the function creation if encapsulated
• Change legacy var to let