fix crash if no SIM card is inserted

res/values/strings.xml

@@ -371,6 +371,10 @@
     <string name="ThreadRecord_draft">Draft:</string>
     <string name="ThreadRecord_media_message">Media message</string>
 
+    <!-- TransportOptions -->
+    <string name="TransportOptions_sms_disabled">SMS messages disabled</string>
+    <string name="TransportOptions_no_sim_card_found">No SIM card found</string>
+
     <!-- VerifyIdentityActivity -->
     <string name="VerifyIdentityActivity_you_do_not_have_an_identity_key">You do not have an identity key.</string>
     <string name="VerifyIdentityActivity_recipient_has_no_identity_key">Recipient has no identity key.</string>

src/org/smssecure/smssecure/ConversationActivity.java

@@ -1300,6 +1300,10 @@ public class ConversationActivity extends PassphraseRequiredActionBarActivity
   }
 
   private void sendMessage() {
+    TransportOption transportOption = sendButton.getSelectedTransport();
+
+    if (transportOption == null || transportOption.getType() == Type.DISABLED) return;
+
     try {
       Recipients recipients = getRecipients();
 

src/org/smssecure/smssecure/TransportOption.java

@@ -12,6 +12,7 @@ import org.whispersystems.libsignal.util.guava.Optional;
 public class TransportOption {
 
   public enum Type {
+    DISABLED,
     INSECURE_SMS,
     SECURE_SMS
   }

src/org/smssecure/smssecure/TransportOptions.java

@@ -8,6 +8,7 @@ import android.support.annotation.Nullable;
 
 import org.smssecure.smssecure.permissions.Permissions;
 import org.smssecure.smssecure.util.CharacterCalculator;
+import org.smssecure.smssecure.util.DummyCharacterCalculator;
 import org.smssecure.smssecure.util.MmsCharacterCalculator;
 import org.smssecure.smssecure.util.SmsCharacterCalculator;
 import org.smssecure.smssecure.util.EncryptedSmsCharacterCalculator;
@@ -99,7 +100,7 @@ public class TransportOptions {
       }
     }
 
-    throw new AssertionError("No options of default type!");
+    return getDefaultTransportOption();
   }
 
   public void disableTransport(Type type) {
@@ -220,4 +221,15 @@ public class TransportOptions {
   public interface OnTransportChangedListener {
     public void onChange(TransportOption newTransport, boolean manuallySelected);
   }
+
+  private TransportOption getDefaultTransportOption() {
+    return new TransportOption(Type.DISABLED,
+                               R.drawable.ic_send_insecure_white_24dp,
+                               context.getResources().getColor(R.color.grey_600),
+                               context.getString(R.string.TransportOptions_sms_disabled),
+                               context.getString(R.string.TransportOptions_no_sim_card_found),
+                               new DummyCharacterCalculator(),
+                               Optional.of((CharSequence) ""),
+                               Optional.of(-1));
+  }
 }

src/org/smssecure/smssecure/util/DummyCharacterCalculator.java

+package org.smssecure.smssecure.util;
+
+public class DummyCharacterCalculator extends CharacterCalculator {
+
+  @Override
+  public CharacterState calculateCharacters(String messageBody) {
+    return new CharacterState(0, 0, 0);
+  }
+}