Fix single character group links crashing.

app/src/main/java/org/thoughtcrime/securesms/groups/v2/GroupInviteLinkUrl.java

@@ -58,7 +58,13 @@ public final class GroupInviteLinkUrl {
         throw new InvalidGroupLinkException("No reference was in the uri");
       }
 
-      byte[]          bytes           = Base64.decode(encoding);
+      byte[] bytes;
+      try {
+        bytes = Base64.decode(encoding);
+      } catch (IllegalArgumentException e) {
+        throw new InvalidGroupLinkException(e);
+      }
+
       GroupInviteLink groupInviteLink = GroupInviteLink.ADAPTER.decode(bytes);
 
       //noinspection SwitchStatementWithTooFewBranches

app/src/test/java/org/thoughtcrime/securesms/groups/v2/GroupInviteLinkUrl_InvalidGroupLinkException_Test.kt

@@ -76,6 +76,15 @@ class GroupInviteLinkUrl_InvalidGroupLinkException_Test {
       .isInstanceOf<IOException>()
   }
 
+  @Test
+  fun one_character_base64_ref() {
+    val uri = "https://signal.group/#A"
+    assertFailure { GroupInviteLinkUrl.fromUri(uri) }
+      .isInstanceOf<InvalidGroupLinkException>()
+      .rootCause()
+      .isInstanceOf<IllegalArgumentException>()
+  }
+
   @Test
   fun bad_protobuf() {
     val uri = "https://signal.group/#CAESNAogpQEzURH6BON1bCS264cmTi37Yi6HTOReXZUEHdsBIgSEPCLfiL7k4wCXmwVi31USVY"