fix: improve error messages for set, map, constructor, and control flow errors

[cs01]

Summary

• Converts 14 throw new Error() calls to emitError() across Set, Map, Literals, control flow, and member access codegen
• Users now see clean error: file.ts:5:3 — Set.add() requires exactly 1 argument instead of a raw JavaScript stack trace

What this means for users

When you make a mistake like calling mySet.add() without arguments, new Set() without a type parameter, or using break outside a loop, you'll now get a clear error message pointing to the exact file and line — instead of an intimidating stack trace that looks like the compiler crashed.

Affected errors

• Set.add/has/delete() argument count
• Map.set/get/has/delete() argument count
• new Set() missing type argument
• new RegExp/Uint8Array/URL() missing arguments
• this keyword outside class context
• break/continue outside loop
• For-loop variable missing initializer

Test plan

• All 451 compiler tests pass
• Self-hosting Stage 0 + Stage 1 pass
• Format check passes

🤖 Generated with Claude Code