throw Exception when no doc.kml file found in kmz

src/main/java/de/dennisguse/opentracks/io/file/importer/KmzTrackImporter.java

@@ -177,6 +177,10 @@ public class KmzTrackImporter implements TrackImporter {
 
                 zipInputStream.closeEntry();
             }
+            if (trackId == null) {
+                Log.d(TAG, "Unable to find doc.kml in kmz");
+                throw new RuntimeException(context.getString(R.string.import_no_kml_file_found));
+            }
             return trackId;
         } catch (ImportParserException | ImportAlreadyExistsException e) {
             Log.e(TAG, "Unable to import file", e);

src/main/res/values/strings.xml

@@ -290,6 +290,7 @@ limitations under the License.
     <string name="import_unsupported_format">Unsupported file format</string>
     <string name="import_parser_error">Parser error: %1$s</string>
     <string name="import_unable_to_import_file">Unable to import file: %1$s</string>
+    <string name="import_no_kml_file_found">No doc.kml file found in KMZ</string>
     <string name="import_error_info">%1$s: %2$s</string>
     <string name="import_error_list_dialog_title">Files not imported</string>
     <string name="import_file_imported">File %1$s imported</string>