all: change optional to result in most of the libraries (#16123)

vlib/encoding/base58/base58_test.v

@@ -1,41 +1,34 @@
 module base58
 
-fn main() {
-	test_encode_int() or {}
-	test_decode_int() or {}
-	test_encode_string()
-	test_fails() or {}
-}
-
-fn test_encode_int() ? {
+fn test_encode_int() {
 	a := 0x24 // should be 'd' in base58
-	assert encode_int(a)? == 'd'
+	assert encode_int(a)! == 'd'
 
-	test_encode_int_walpha()?
+	test_encode_int_walpha()
 }
 
-fn test_encode_int_walpha() ? {
+fn test_encode_int_walpha() {
 	// random alphabet
 	abc := new_alphabet('abcdefghij\$lmnopqrstuvwxyz0123456789_ABCDEFGHIJLMNOPQRSTUV') or {
 		panic(@MOD + '.' + @FN + ': this should never happen')
 	}
 	a := 0x24 // should be '_' in base58 with our custom alphabet
-	assert encode_int_walpha(a, abc)? == '_'
+	assert encode_int_walpha(a, abc)! == '_'
 }
 
-fn test_decode_int() ? {
+fn test_decode_int() {
 	a := 'd'
-	assert decode_int(a)? == 0x24
+	assert decode_int(a)! == 0x24
 
-	test_decode_int_walpha()?
+	test_decode_int_walpha()
 }
 
-fn test_decode_int_walpha() ? {
+fn test_decode_int_walpha() {
 	abc := new_alphabet('abcdefghij\$lmnopqrstuvwxyz0123456789_ABCDEFGHIJLMNOPQRSTUV') or {
 		panic(@MOD + '.' + @FN + ': this should never happen')
 	}
 	a := '_'
-	assert decode_int_walpha(a, abc)? == 0x24
+	assert decode_int_walpha(a, abc)! == 0x24
 }
 
 fn test_encode_string() {
@@ -49,18 +42,18 @@ fn test_encode_string() {
 	assert encode_walpha(a, abc) == '0P7yfPSL0pQh2L5'
 }
 
-fn test_decode_string() ? {
+fn test_decode_string() {
 	a := 'TtaR6twpTGu8VpY'
-	assert decode(a)? == 'lorem ipsum'
+	assert decode(a)! == 'lorem ipsum'
 
 	abc := new_alphabet('abcdefghij\$lmnopqrstuvwxyz0123456789_ABCDEFGHIJLMNOPQRSTUV') or {
 		panic(@MOD + '.' + @FN + ': this should never happen')
 	}
 	b := '0P7yfPSL0pQh2L5'
-	assert decode_walpha(b, abc)? == 'lorem ipsum'
+	assert decode_walpha(b, abc)! == 'lorem ipsum'
 }
 
-fn test_fails() ? {
+fn test_fails() ! {
 	a := -238
 	b := 0
 	if z := encode_int(a) {