Utilize `union #shared_nil` in more places

core/bufio/scanner.odin

@@ -8,6 +8,7 @@ import "core:intrinsics"
 
 // Extra errors returns by scanning procedures
 Scanner_Extra_Error :: enum i32 {
+	None,
 	Negative_Advance,
 	Advanced_Too_Far,
 	Bad_Read_Count,
@@ -15,7 +16,7 @@ Scanner_Extra_Error :: enum i32 {
 	Too_Short,
 }
 
-Scanner_Error :: union {
+Scanner_Error :: union #shared_nil {
 	io.Error,
 	Scanner_Extra_Error,
 }
@@ -68,7 +69,7 @@ scanner_destroy :: proc(s: ^Scanner) {
 // Returns the first non-EOF error that was encounted by the scanner
 scanner_error :: proc(s: ^Scanner) -> Scanner_Error {
 	switch s._err {
-	case .EOF, .None:
+	case .EOF, nil:
 		return nil
 	}
 	return s._err
@@ -93,10 +94,6 @@ scanner_text :: proc(s: ^Scanner) -> string {
 // scanner_scan advances the scanner
 scanner_scan :: proc(s: ^Scanner) -> bool {
 	set_err :: proc(s: ^Scanner, err: Scanner_Error) {
-		err := err
-		if err == .None {
-			err = nil
-		}
 		switch s._err {
 		case nil, .EOF:
 			s._err = err

core/compress/zlib/zlib.odin

@@ -47,7 +47,7 @@ Options :: struct {
 	level: u8,
 }
 
-Error     :: compress.Error
+Error         :: compress.Error
 General_Error :: compress.General_Error
 ZLIB_Error    :: compress.ZLIB_Error
 Deflate_Error :: compress.Deflate_Error

core/encoding/json/marshal.odin

@@ -8,17 +8,18 @@ import "core:strings"
 import "core:io"
 
 Marshal_Data_Error :: enum {
+	None,
 	Unsupported_Type,
 }
 
-Marshal_Error :: union {
+Marshal_Error :: union #shared_nil {
 	Marshal_Data_Error,
 	io.Error,
 }
 
 marshal :: proc(v: any, allocator := context.allocator) -> (data: []byte, err: Marshal_Error) {
 	b := strings.make_builder(allocator)
-	defer if err != .None {
+	defer if err != nil {
 		strings.destroy_builder(&b)
 	}
 
@@ -27,7 +28,7 @@ marshal :: proc(v: any, allocator := context.allocator) -> (data: []byte, err: M
 	if len(b.buf) != 0 {
 		data = b.buf[:]
 	}
-	return data, .None
+	return data, nil
 }
 
 marshal_to_builder :: proc(b: ^strings.Builder, v: any) -> Marshal_Error {