feat: Improve error messages for now-failing-missing-config-file

Author: hoelger

fed/mosaic-output/src/main/java/org/eclipse/mosaic/fed/output/ambassador/OutputAmbassador.java

@@ -35,6 +35,7 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.io.FileNotFoundException;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
@@ -154,6 +155,8 @@ private Collection<OutputGeneratorLoader> loadConfiguration() {
 
             // do not yet create output generators. This is done when the ambassadors initialize method is called
             return generatorLoader.values();
+        } catch (FileNotFoundException e) {
+            throw new RuntimeException("Configuration file not found. Consider turning off the output ambassador in scenario_config.json", e);
         } catch (InternalFederateException | IllegalArgumentException | IllegalStateException | IOException e) {
             throw new RuntimeException(e);
         } catch (Exception ex) {

lib/mosaic-utils/src/main/java/org/eclipse/mosaic/lib/util/XmlUtils.java

@@ -24,6 +24,7 @@
 import org.apache.commons.lang3.ObjectUtils;
 
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
@@ -53,6 +54,9 @@ protected Transformer createTransformer() throws ConfigurationException {
     }
 
     public static XMLConfiguration readXmlFromFile(File file) throws IOException {
+        if (!file.exists() || !file.isFile()) {
+            throw new FileNotFoundException(file.getAbsolutePath() + " cannot be found");
+        }
         final XMLConfiguration configuration = createEmptyConfigurationWithIndentation(DEFAULT_XML_INDENTATION);
         try {
             new FileHandler(configuration).load(file);