Skip async errors for inactive sessions

app/src/main/java/eu/faircode/email/Core.java

@@ -4052,7 +4052,8 @@ class Core {
     }
 
     static class State {
-        private int session;
+        private int session = -1;
+        private boolean active = false;
         private int backoff;
         private ConnectionHelper.NetworkState networkState;
         private Thread thread = new Thread();
@@ -4103,11 +4104,16 @@ class Core {
         }
 
         void error(Throwable ex, int session) {
-            if (session != this.session) {
-                Log.i("Ignoring session=" + session + "/" + this.session + " ex=" + ex);
+            if (!this.active || session != this.session) {
+                Log.i("Ignoring" +
+                        " active=" + active +
+                        " session=" + session + "/" + this.session +
+                        " ex=" + ex);
                 return;
             }
 
+            active = false;
+
             if (ex instanceof MessagingException &&
                     ("connection failure".equals(ex.getMessage()) ||
                             "Not connected".equals(ex.getMessage()) || // POP3
@@ -4140,11 +4146,16 @@ class Core {
 
         void reset(int run) {
             session = run;
+            active = true;
             recoverable = true;
             lastActivity = null;
             resetBatches();
         }
 
+        void setActive(boolean whether) {
+            this.active = whether;
+        }
+
         void resetBatches() {
             synchronized (this) {
                 for (FolderPriority key : sequence.keySet()) {

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -1543,6 +1543,8 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
 
                     Log.i(account.name + " done state=" + state);
                 } catch (Throwable ex) {
+                    state.setActive(false);
+
                     Log.e(account.name, ex);
                     EntityLog.log(
                             ServiceSynchronize.this,
@@ -1587,6 +1589,8 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                         }
                     }
                 } finally {
+                    state.setActive(false);
+
                     // Update state
                     EntityLog.log(this, account.name + " closing");
                     db.account().setAccountState(account.id, "closing");