CtrlC and CtrlD tweaks on terminal device and Kill MCP

- Just a few notes. This will be fixed later at the MCP. CtrlC and CtrlD at the
Blink Shell are special modes as the shell doesn't use readline. This should be
fixed at the MCP itself.

Blink/TermDevice.m

@@ -216,12 +216,15 @@ - (void)write:(NSString *)input
   if ([input isEqualToString:ctrlC] || [input isEqualToString:ctrlD]) {
     [self closeReadline];
 
-    //if ([input isEqualToString:ctrlD]) {
-    [self _EOT];
-    if ([input isEqualToString: ctrlC]) {
-      fprintf(_stream.err, "^C\n");
+    if (_readlineSema) {
+      [self _EOT];
+      if ([input isEqualToString: ctrlC]) {
+        fprintf(_stream.err, "^C\n");
+      }
+      if ([input isEqualToString: ctrlD]) {
+        fprintf(_stream.err, "^D\n");
+      }
     }
-    //}
     // NOTE This should send specific signals instead of handling the control openly, but won't change for now.
     [self.delegate handleControl: input];
     return;
@@ -233,6 +236,7 @@ - (void)write:(NSString *)input
     return;
   }
 
+  // On Blink prompt, atm this is a special mode as it doesn't have a "readline" per-se.
   [self.view processKB:input];
 }
 

Sessions/MCPSession.m

@@ -113,7 +113,9 @@ - (void)executeWithArgs:(NSString *)args {
         [_device prompt:@"blink> " secure:NO shell:YES];
       }
     #else
-    [_device prompt:@"blink> " secure:NO shell:YES];
+    if (_device) {
+      [_device prompt:@"blink> " secure:NO shell:YES];
+    }
     #endif
   });
 }
@@ -236,7 +238,12 @@ - (BOOL)_runCommand:(NSString *)cmdline skipHistoryRecord: (BOOL) skipHistoryRec
     setlocale(LC_CTYPE, "UTF-8");
   }
 
-  [_device prompt:@"blink> " secure:NO shell:YES];
+  if (_device) {
+    // TODO At the moment this is just a prompt instead of a readline. This needs to be fixed.
+    // And bc of that, we need to check that there is a device. The MCP may be killed, but the loop here may still
+    // try to write to the device.
+    [_device prompt:@"blink> " secure:NO shell:YES];
+  }
 
   return YES;
 }
@@ -357,6 +364,7 @@ - (void)kill
   ios_closeSession(_sessionUUID.UTF8String);
 
   [_device close];
+  _device = NULL;
 }
 
 - (void)suspend