securejoin: replace thiserror with anyhow

Refactoring to reduce the number of custom error types.

src/securejoin/bob.rs

@@ -3,7 +3,7 @@
 //! This are some helper functions around [`BobState`] which augment the state changes with
 //! the required user interactions.
 
-use anyhow::Result;
+use anyhow::{Context as _, Result};
 
 use crate::chat::{is_contact_in_chat, ChatId, ProtectionStatus};
 use crate::constants::{Blocked, Chattype};
@@ -16,7 +16,7 @@ use crate::{chat, stock_str};
 
 use super::bobstate::{BobHandshakeStage, BobState};
 use super::qrinvite::QrInvite;
-use super::{HandshakeMessage, JoinError};
+use super::HandshakeMessage;
 
 /// Starts the securejoin protocol with the QR `invite`.
 ///
@@ -30,10 +30,7 @@ use super::{HandshakeMessage, JoinError};
 ///
 /// The [`ChatId`] of the created chat is returned, for a SetupContact QR this is the 1:1
 /// chat with Alice, for a SecureJoin QR this is the group chat.
-pub(super) async fn start_protocol(
-    context: &Context,
-    invite: QrInvite,
-) -> Result<ChatId, JoinError> {
+pub(super) async fn start_protocol(context: &Context, invite: QrInvite) -> Result<ChatId> {
     // A 1:1 chat is needed to send messages to Alice.  When joining a group this chat is
     // hidden, if a user starts sending messages in it it will be unhidden in
     // dc_receive_imf.
@@ -43,7 +40,7 @@ pub(super) async fn start_protocol(
     };
     let chat_id = ChatId::create_for_contact_with_blocked(context, invite.contact_id(), hidden)
         .await
-        .map_err(JoinError::UnknownContact)?;
+        .with_context(|| format!("can't create chat for contact {}", invite.contact_id()))?;
 
     // Now start the protocol and initialise the state
     let (state, stage, aborted_states) =

src/securejoin/bobstate.rs

@@ -22,9 +22,7 @@ use crate::param::Param;
 use crate::sql::Sql;
 
 use super::qrinvite::QrInvite;
-use super::{
-    encrypted_and_signed, fingerprint_equals_sender, mark_peer_as_verified, JoinError, SendMsgError,
-};
+use super::{encrypted_and_signed, fingerprint_equals_sender, mark_peer_as_verified};
 
 /// The stage of the [`BobState`] securejoin handshake protocol state machine.
 ///
@@ -94,7 +92,7 @@ impl BobState {
         context: &Context,
         invite: QrInvite,
         chat_id: ChatId,
-    ) -> Result<(Self, BobHandshakeStage, Vec<Self>), JoinError> {
+    ) -> Result<(Self, BobHandshakeStage, Vec<Self>)> {
         let (stage, next) =
             if fingerprint_equals_sender(context, invite.fingerprint(), invite.contact_id()).await?
             {
@@ -404,11 +402,7 @@ impl BobState {
     /// Sends the requested handshake message to Alice.
     ///
     /// This takes care of adding the required headers for the step.
-    async fn send_handshake_message(
-        &self,
-        context: &Context,
-        step: BobHandshakeMsg,
-    ) -> Result<(), SendMsgError> {
+    async fn send_handshake_message(&self, context: &Context, step: BobHandshakeMsg) -> Result<()> {
         send_handshake_message(context, &self.invite, self.chat_id, step).await
     }
 }
@@ -422,7 +416,7 @@ async fn send_handshake_message(
     invite: &QrInvite,
     chat_id: ChatId,
     step: BobHandshakeMsg,
-) -> Result<(), SendMsgError> {
+) -> Result<()> {
     let mut msg = Message {
         viewtype: Viewtype::Text,
         text: Some(step.body_text(invite)),