crypto: add custom errors to crypto lib (#9522)

vlib/crypto/rand/rand.v

@@ -4,6 +4,7 @@
 
 module rand
 
-const (
-	read_error = error('crypto.rand.read() error reading random bytes')
-)
+struct ReadError {
+	msg  string = 'crypto.rand.read() error reading random bytes'
+	code int
+}

vlib/crypto/rand/rand_darwin.c.v

@@ -15,7 +15,7 @@ pub fn read(bytes_needed int) ?[]byte {
 	mut buffer := []byte{len: bytes_needed}
 	status := C.SecRandomCopyBytes(C.SecRandomRef(0), bytes_needed, buffer.data)
 	if status != 0 {
-		return read_error
+		return IError(&ReadError{})
 	}
 	return buffer
 }

vlib/crypto/rand/rand_linux.c.v

@@ -19,7 +19,7 @@ pub fn read(bytes_needed int) ?[]byte {
 		rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
 		if rbytes == -1 {
 			unsafe { free(buffer) }
-			return read_error
+			return IError(&ReadError{})
 		}
 		bytes_read += rbytes
 	}

vlib/crypto/rand/rand_solaris.c.v

@@ -23,7 +23,7 @@ pub fn read(bytes_needed int) ?[]byte {
 		rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
 		if rbytes == -1 {
 			unsafe { free(buffer) }
-			return read_error
+			return IError(&ReadError{})
 		}
 		bytes_read += rbytes
 	}

vlib/crypto/rand/rand_windows.c.v

@@ -19,7 +19,7 @@ pub fn read(bytes_needed int) ?[]byte {
 	// use bcrypt_use_system_preferred_rng because we passed null as algo
 	status := C.BCryptGenRandom(0, buffer.data, bytes_needed, bcrypt_use_system_preferred_rng)
 	if status != status_success {
-		return read_error
+		return IError(&ReadError{})
 	}
 	return buffer
 }