guard int32/uint32 map key narrowing in qualifyInternal

[alhudz]

Repro: indexing a native map[int32]any with a key outside the int32 range, e.g. m[4294967296] where m == {0: "x"}, returns "x" instead of a no-such-key error. Same for map[uint32]any.
Cause: intQualifier.qualifyInternal and uintQualifier.qualifyInternal cast the int64/uint64 index to int32/uint32 before the lookup, so 4294967296 wraps to 0 and collides with the entry stored at key 0.
Fix: only perform the narrowed lookup when the index round-trips through the key type (int64(int32(i)) == i), otherwise fall through to the existing missing-key path.

[TristonianJones]

/gcbrun