Added type checks

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

@@ -192,9 +192,11 @@ public class EntityCertificate {
             Collection<List<?>> altNames = certificate.getSubjectAlternativeNames();
             if (altNames != null)
                 for (List altName : altNames)
-                    if (altName.get(0).equals(GeneralName.rfc822Name))
+                    if (altName.get(0).equals(GeneralName.rfc822Name)) {
+                        if (altName.get(1) instanceof String)
                             result.add((String) altName.get(1));
-                    else if (altName.get(0).equals(GeneralName.otherName) && altName.get(1) instanceof byte[])
+                    } else if (altName.get(0).equals(GeneralName.otherName)) {
+                        if (altName.get(1) instanceof byte[])
                             try {
                                 ASN1InputStream decoder = new ASN1InputStream((byte[]) altName.get(1));
                                 DLTaggedObject encoded = (DLTaggedObject) decoder.readObject();
@@ -210,7 +212,7 @@ public class EntityCertificate {
                             } catch (Throwable ex) {
                                 Log.w(ex);
                             }
-                    else
+                    } else
                         Log.i("Alt type=" + altName.get(0) + " data=" + altName.get(1));
         } catch (CertificateParsingException ex) {
             Log.e(ex);
@@ -252,9 +254,10 @@ public class EntityCertificate {
 
         for (List altName : altNames)
             try {
-                if (altName.get(0).equals(GeneralName.dNSName))
+                if (altName.get(0).equals(GeneralName.dNSName)) {
+                    if (altName.get(1) instanceof String)
                         result.add((String) altName.get(1));
-                else if (altName.get(0).equals(GeneralName.iPAddress))
+                } else if (altName.get(0).equals(GeneralName.iPAddress))
                     if (altName.get(1) instanceof String)
                         result.add((String) altName.get(1));
                     else {