docs(firebase_auth): Removed duplicates; fixed typos; removed "unnecessary use of a null check" (#16815)

Co-authored-by: Russell Wheatley <[email protected]>

Author: Nikita0x

packages/firebase_auth/firebase_auth/lib/src/firebase_auth.dart

@@ -220,8 +220,8 @@ class FirebaseAuth extends FirebasePluginPlatform {
   ///  - Thrown if the user is no longer authenticated since his refresh token
   ///    has been expired
   /// - **network-request-failed**:
-  ///  - Thrown if there was a network request error, for example the user don't
-  ///    don't have internet connection
+  ///  - Thrown if there was a network request error, for example the user
+  ///    doesn't have internet connection
   /// - **operation-not-allowed**:
   ///  - Thrown if email/password accounts are not enabled. Enable
   ///    email/password accounts in the Firebase Console, under the Auth tab.
@@ -498,7 +498,7 @@ class FirebaseAuth extends FirebasePluginPlatform {
   ///    verification code of the credential is not valid.
   /// - **invalid-verification-id**:
   ///  - Thrown if the credential is a [PhoneAuthProvider.credential] and the
-  ///    verification ID of the credential is not valid.id.
+  ///    verification ID of the credential is not valid.
   Future<UserCredential> signInWithCredential(AuthCredential credential) async {
     try {
       return UserCredential._(
@@ -570,12 +570,12 @@ class FirebaseAuth extends FirebasePluginPlatform {
   ///  - Thrown if the user is no longer authenticated since his refresh token
   ///    has been expired
   /// - **network-request-failed**:
-  ///  - Thrown if there was a network request error, for example the user don't
-  ///    don't have internet connection
+  ///  - Thrown if there was a network request error, for example the user
+  ///    doesn't have internet connection
   /// - **INVALID_LOGIN_CREDENTIALS** or **invalid-credential**:
   ///  - Thrown if the password is invalid for the given email, or the account
   ///    corresponding to the email does not have a password set.
-  ///    depending on if you are using firebase emulator or not the code is
+  ///    Depending on if you are using firebase emulator or not the code is
   ///    different
   /// - **operation-not-allowed**:
   ///  - Thrown if email/password accounts are not enabled. Enable

packages/firebase_auth/firebase_auth_platform_interface/lib/src/platform_interface/platform_interface_firebase_auth.dart

@@ -236,8 +236,8 @@ abstract class FirebaseAuthPlatform extends PlatformInterface {
   ///  - Thrown if the user is no longer authenticated since his refresh token
   ///    has been expired
   /// - **network-request-failed**:
-  ///  - Thrown if there was a network request error, for example the user don't
-  ///    don't have internet connection
+  ///  - Thrown if there was a network request error, for example the user
+  ///    doesn't have internet connection
   /// - **operation-not-allowed**:
   ///  - Thrown if email/password accounts are not enabled. Enable
   ///    email/password accounts in the Firebase Console, under the Auth tab.
@@ -476,7 +476,7 @@ abstract class FirebaseAuthPlatform extends PlatformInterface {
   ///    verification code of the credential is not valid.
   /// - **invalid-verification-id**:
   ///  - Thrown if the credential is a [PhoneAuthProvider.credential] and the
-  ///    verification ID of the credential is not valid.id.
+  ///    verification ID of the credential is not valid.
   Future<UserCredentialPlatform> signInWithCredential(
     AuthCredential credential,
   ) async {
@@ -527,12 +527,12 @@ abstract class FirebaseAuthPlatform extends PlatformInterface {
   ///  - Thrown if the user is no longer authenticated since his refresh token
   ///    has been expired
   /// - **network-request-failed**:
-  ///  - Thrown if there was a network request error, for example the user don't
-  ///    don't have internet connection
+  ///  - Thrown if there was a network request error, for example the user
+  ///    doesn't have internet connection
   /// - **INVALID_LOGIN_CREDENTIALS** or **invalid-credential**:
   ///  - Thrown if the password is invalid for the given email, or the account
   ///    corresponding to the email does not have a password set.
-  ///    depending on if you are using firebase emulator or not the code is
+  ///    Depending on if you are using firebase emulator or not the code is
   ///    different
   /// - **operation-not-allowed**:
   ///  - Thrown if email/password accounts are not enabled. Enable