COMPLETED

Test Function: TestMultiValueReturnEdgeCases
File: /Users/jack/mag/dingo/pkg/preprocessor/preprocessor_test.go
Lines: 798-1054 (257 lines added)

Test Cases: 10/10 PASSED
- 2-value return (baseline case) ✓
- 3-value return (verified by golden test) ✓
- 4-value return (extreme case) ✓
- 5-value return (very extreme case) ✓
- mixed types (string, int, []byte, error) ✓
- complex types (map, slice, struct pointer, error) ✓
- verify correct number of temporaries (3 non-error values) ✓
- verify correct number of temporaries (4 non-error values) ✓
- all values returned in success path (4 values) ✓
- all zero values in error path (mixed types) ✓

Execution Time: 0.185s
Status: All tests pass successfully

Verification Command:
go test ./pkg/preprocessor -run '^TestMultiValueReturnEdgeCases$' -v

Notes:
- Comprehensive coverage beyond existing error_prop_09_multi_value golden test
- Tests 2-5 value returns with various type combinations
- Verifies correct temporary variable counts (__tmp0, __tmp1, etc.)
- Ensures all values returned in success path
- Confirms all zero values in error path
- Prevents CRITICAL-2 regression (multi-value return dropping)
