pgm: Handle exceptions in Config command

This avoids we show a stacktrace on the console by default when this
type of exception is thrown during the run method is executed. Also
externalize error message.

Change-Id: I909dc77385a672d8298053b12683c0cbbf9f2aa2
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.pgm/resources/org/eclipse/jgit/pgm/internal/CLIText.properties

@@ -51,6 +51,7 @@ cleanRequireForce=clean.requireForce defaults to true and neither -n nor -f give
 clonedEmptyRepository=warning: You appear to have cloned an empty repository.
 cloningInto=Cloning into ''{0}''...
 commitLabel=commit
+configOnlyListOptionSupported=only the --list option is currently supported
 configFileNotFound=configuration file {0} not found
 conflictingUsageOf_git_dir_andArguments=conflicting usage of --git-dir and arguments
 couldNotCreateBranch=Could not create branch {0}: {1}

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Config.java

@@ -42,9 +42,9 @@ import java.io.IOException;
 import java.util.Set;
 
 import org.eclipse.jgit.errors.ConfigInvalidException;
-import org.eclipse.jgit.errors.NotSupportedException;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.StoredConfig;
+import org.eclipse.jgit.pgm.internal.CLIText;
 import org.eclipse.jgit.storage.file.FileBasedConfig;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.StringUtils;
@@ -70,12 +70,15 @@ class Config extends TextBuiltin {
 
 	/** {@inheritDoc} */
 	@Override
-	protected void run() throws Exception {
-		if (list)
+	protected void run() {
+		if (!list) {
+			throw die(CLIText.get().configOnlyListOptionSupported);
+		}
+		try {
 			list();
-		else
-			throw new NotSupportedException(
-					"only --list option is currently supported"); //$NON-NLS-1$
+		} catch (IOException | ConfigInvalidException e) {
+			throw die(e.getMessage(), e);
+		}
 	}
 
 	private void list() throws IOException, ConfigInvalidException {

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/internal/CLIText.java

@@ -165,6 +165,7 @@ public class CLIText extends TranslationBundle {
 	/***/ public String clonedEmptyRepository;
 	/***/ public String cloningInto;
 	/***/ public String commitLabel;
+	/***/ public String configOnlyListOptionSupported;
 	/***/ public String conflictingUsageOf_git_dir_andArguments;
 	/***/ public String couldNotCreateBranch;
 	/***/ public String dateInfo;