lang: Add AccountNotInitialized error and checks for it

- Add `AccountInitialized` trait
    - For `AccountInfo` implement it directly for prevent clone
- Add `ErrorCode::AccountNotInitialized`
- Add check for it in `Account::try_from` & `Account::try_from_unchecked`
- Add check in `ProgramAccount::try_from` & `ProgramAccount::try_from_unchecked`
    - Yes this type deprecated, but until it is removed from the repository, it seems to me not superfluous to add this check to it
- Add `ErrorCode::StateNotInitialized`
- Add check in `State::try_from`
- Improve documentation for `AccountInitialized` trait
- Add `AccountNotInitialized` & `StateNotInitialized` to error.ts

lang/src/account.rs

@@ -22,6 +22,9 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Owner + Clone> Account<'a, T
     /// Deserializes the given `info` into a `Account`.
     #[inline(never)]
     pub fn try_from(info: &AccountInfo<'a>) -> Result<Account<'a, T>, ProgramError> {
+        if info.not_initialized() {
+            return Err(ErrorCode::AccountNotInitialized.into());
+        }
         if info.owner != &T::owner() {
             return Err(ErrorCode::AccountNotProgramOwned.into());
         }
@@ -34,6 +37,9 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Owner + Clone> Account<'a, T
     /// possible.
     #[inline(never)]
     pub fn try_from_unchecked(info: &AccountInfo<'a>) -> Result<Account<'a, T>, ProgramError> {
+        if info.not_initialized() {
+            return Err(ErrorCode::AccountNotInitialized.into());
+        }
         if info.owner != &T::owner() {
             return Err(ErrorCode::AccountNotProgramOwned.into());
         }

lang/src/account_info.rs

@@ -1,10 +1,13 @@
 use crate::error::ErrorCode;
-use crate::{Accounts, AccountsExit, Key, ToAccountInfo, ToAccountInfos, ToAccountMetas};
+use crate::{
+    AccountInitialized, Accounts, AccountsExit, Key, ToAccountInfo, ToAccountInfos, ToAccountMetas,
+};
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
 use solana_program::instruction::AccountMeta;
 use solana_program::program_error::ProgramError;
 use solana_program::pubkey::Pubkey;
+use solana_program::system_program;
 
 impl<'info> Accounts<'info> for AccountInfo<'info> {
     fn try_accounts(
@@ -56,3 +59,12 @@ impl<'info> Key for AccountInfo<'info> {
         *self.key
     }
 }
+
+impl<'info> AccountInitialized<'info> for AccountInfo<'info> {
+    fn initialized(&self) -> bool {
+        self.lamports() == 0 && system_program::ID.eq(self.owner)
+    }
+    fn not_initialized(&self) -> bool {
+        !self.initialized()
+    }
+}

lang/src/error.rs

@@ -74,10 +74,14 @@ pub enum ErrorCode {
     AccountNotSigner,
     #[msg("The given account is not owned by the system program")]
     AccountNotSystemOwned,
+    #[msg("The program expected this account to be already initialized")]
+    AccountNotInitialized,
 
     // State.
     #[msg("The given state account does not have the correct address")]
     StateInvalidAddress = 180,
+    #[msg("The given state account does not initialized")]
+    StateNotInitialized,
 
     // Used for APIs that shouldn't be used anymore.
     #[msg("The API being used is deprecated and should no longer be used")]

lang/src/lib.rs

@@ -154,6 +154,31 @@ pub trait ToAccountInfo<'info> {
     fn to_account_info(&self) -> AccountInfo<'info>;
 }
 
+/// Allows you to check if a given account is initialized or not
+pub trait AccountInitialized<'info>: ToAccountInfo<'info> {
+    /// Checks if account initialized by call
+    /// [`CreateAccount`](solana_program::system_instruction::SystemInstruction::CreateAccount)
+    /// or [CreateAccountWithSeed](`solana_program::system_instruction::SystemInstruction::CreateAccountWithSeed`)
+    /// solana system instructions
+    ///
+    /// According to the [documentation](https://docs.solana.com/developing/programming-model/accounts#creating),
+    /// an uninitialized account has 0 [lamports](AccountInfo::lamports) and has a [system program](solana_program::system_program) [owner](AccountInfo::owner)
+    fn initialized(&self) -> bool {
+        !self.not_initialized()
+    }
+    /// Checks if account not initialized by call
+    /// [`CreateAccount`](solana_program::system_instruction::SystemInstruction::CreateAccount)
+    /// or [CreateAccountWithSeed](`solana_program::system_instruction::SystemInstruction::CreateAccountWithSeed`)
+    /// solana system instructions
+    ///
+    /// According to the [documentation](https://docs.solana.com/developing/programming-model/accounts#creating),
+    /// an uninitialized account has 0 [lamports](AccountInfo::lamports) and has a [system program](solana_program::system_program) [owner](AccountInfo::owner)
+    fn not_initialized(&self) -> bool {
+        let account_info = self.to_account_info();
+        account_info.lamports() == 0 && system_program::ID.eq(account_info.owner)
+    }
+}
+
 /// A data structure that can be serialized and stored into account storage,
 /// i.e. an
 /// [`AccountInfo`](../solana_program/account_info/struct.AccountInfo.html#structfield.data)'s

lang/src/program_account.rs

@@ -2,8 +2,8 @@ use crate::error::ErrorCode;
 #[allow(deprecated)]
 use crate::CpiAccount;
 use crate::{
-    AccountDeserialize, AccountSerialize, Accounts, AccountsClose, AccountsExit, Key,
-    ToAccountInfo, ToAccountInfos, ToAccountMetas,
+    AccountDeserialize, AccountInitialized, AccountSerialize, Accounts, AccountsClose,
+    AccountsExit, Key, ToAccountInfo, ToAccountInfos, ToAccountMetas,
 };
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
@@ -40,6 +40,9 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Clone> ProgramAccount<'a, T>
         program_id: &Pubkey,
         info: &AccountInfo<'a>,
     ) -> Result<ProgramAccount<'a, T>, ProgramError> {
+        if info.not_initialized() {
+            return Err(ErrorCode::AccountNotInitialized.into());
+        }
         if info.owner != program_id {
             return Err(ErrorCode::AccountNotProgramOwned.into());
         }
@@ -58,6 +61,9 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Clone> ProgramAccount<'a, T>
         program_id: &Pubkey,
         info: &AccountInfo<'a>,
     ) -> Result<ProgramAccount<'a, T>, ProgramError> {
+        if info.not_initialized() {
+            return Err(ErrorCode::AccountNotInitialized.into());
+        }
         if info.owner != program_id {
             return Err(ErrorCode::AccountNotProgramOwned.into());
         }

lang/src/state.rs

@@ -2,8 +2,8 @@ use crate::error::ErrorCode;
 #[allow(deprecated)]
 use crate::CpiAccount;
 use crate::{
-    AccountDeserialize, AccountSerialize, Accounts, AccountsExit, Key, ToAccountInfo,
-    ToAccountInfos, ToAccountMetas,
+    AccountDeserialize, AccountInitialized, AccountSerialize, Accounts, AccountsExit, Key,
+    ToAccountInfo, ToAccountInfos, ToAccountMetas,
 };
 use solana_program::account_info::AccountInfo;
 use solana_program::entrypoint::ProgramResult;
@@ -42,6 +42,9 @@ impl<'a, T: AccountSerialize + AccountDeserialize + Clone> ProgramState<'a, T> {
         program_id: &Pubkey,
         info: &AccountInfo<'a>,
     ) -> Result<ProgramState<'a, T>, ProgramError> {
+        if info.not_initialized() {
+            return Err(ErrorCode::StateNotInitialized.into());
+        }
         if info.owner != program_id {
             return Err(ErrorCode::AccountNotProgramOwned.into());
         }

ts/src/error.ts

@@ -89,9 +89,11 @@ const LangErrorCode = {
   InvalidProgramExecutable: 169,
   AccountNotSigner: 170,
   AccountNotSystemOwned: 171,
+  AccountNotInitialized: 172,
 
   // State.
   StateInvalidAddress: 180,
+  StateNotInitialized: 181,
 
   // Used for APIs that shouldn't be used anymore.
   Deprecated: 299,
@@ -175,12 +177,20 @@ const LangErrorMessage = new Map([
     LangErrorCode.AccountNotSystemOwned,
     "The given account is not owned by the system program",
   ],
+  [
+    LangErrorCode.AccountNotInitialized,
+    "The program expected this account to be already initialized",
+  ],
 
   // State.
   [
     LangErrorCode.StateInvalidAddress,
     "The given state account does not have the correct address",
   ],
+  [
+    LangErrorCode.StateNotInitialized,
+    "The given state account does not initialized",
+  ],
 
   // Misc.
   [