chore(gui): regex search: make searchField background red in case of invalid regex entered

jadx-gui/src/main/java/jadx/gui/ui/SearchDialog.java

 package jadx.gui.ui;
 
-import java.awt.BorderLayout;
-import java.awt.Container;
-import java.awt.Dimension;
-import java.awt.FlowLayout;
+import java.awt.*;
 import java.awt.event.KeyAdapter;
 import java.awt.event.KeyEvent;
 import java.util.Collections;
@@ -38,10 +35,12 @@ import jadx.gui.treemodel.JNode;
 import jadx.gui.utils.NLS;
 import jadx.gui.utils.TextStandardActions;
 import jadx.gui.utils.layout.WrapLayout;
+import jadx.gui.utils.search.SearchSettings;
 import jadx.gui.utils.search.TextSearchIndex;
 
 public class SearchDialog extends CommonSearchDialog {
 	private static final long serialVersionUID = -5105405456969134105L;
+	private static final Color SEARCHFIELD_ERROR_COLOR = new Color(255, 150, 150);
 
 	private static final Logger LOG = LoggerFactory.getLogger(SearchDialog.class);
 
@@ -81,6 +80,8 @@ public class SearchDialog extends CommonSearchDialog {
 	private final transient SearchPreset searchPreset;
 	private final transient Set<SearchOptions> options;
 
+	private Color searchFieldDefaultBgColor;
+
 	private transient JTextField searchField;
 
 	private transient Disposable searchDisposable;
@@ -183,6 +184,7 @@ public class SearchDialog extends CommonSearchDialog {
 
 	private void initUI() {
 		searchField = new JTextField();
+		searchFieldDefaultBgColor = searchField.getBackground();
 		searchField.setAlignmentX(LEFT_ALIGNMENT);
 		TextStandardActions.attach(searchField);
 
@@ -304,7 +306,16 @@ public class SearchDialog extends CommonSearchDialog {
 		}
 		LOG.debug("search event: {}", text);
 		showSearchState();
-		return index.buildSearch(text, options);
+		try {
+			Flowable<JNode> result = index.buildSearch(text, options);
+			if (searchField.getBackground() == SEARCHFIELD_ERROR_COLOR) {
+				searchField.setBackground(searchFieldDefaultBgColor);
+			}
+			return result;
+		} catch (SearchSettings.InvalidSearchTermException e) {
+			searchField.setBackground(SEARCHFIELD_ERROR_COLOR);
+			return Flowable.empty();
+		}
 	}
 
 	private void processSearchResults(java.util.List<JNode> results) {

jadx-gui/src/main/java/jadx/gui/utils/search/SearchSettings.java

@@ -52,14 +52,13 @@ public class SearchSettings {
 		return this.regexPattern;
 	}
 
-	public boolean preCompile() {
+	public boolean preCompile() throws InvalidSearchTermException {
 		if (useRegex) {
 			try {
 				int flags = ignoreCase ? Pattern.CASE_INSENSITIVE : 0;
 				this.regexPattern = Pattern.compile(searchString, flags);
 			} catch (Exception e) {
-				LOG.warn("Invalid Regex: {}", this.searchString, e);
-				return false;
+				throw new InvalidSearchTermException("Invalid Regex: " + this.searchString, e);
 			}
 		}
 		return true;
@@ -105,4 +104,11 @@ public class SearchSettings {
 	public void setActiveCls(JClass activeCls) {
 		this.activeCls = activeCls;
 	}
+
+	public static class InvalidSearchTermException extends Exception {
+
+		public InvalidSearchTermException(String message, Throwable cause) {
+			super(message, cause);
+		}
+	}
 }

jadx-gui/src/main/java/jadx/gui/utils/search/TextSearchIndex.java

@@ -109,7 +109,8 @@ public class TextSearchIndex {
 		this.codeIndex.removeForCls(cls);
 	}
 
-	public Flowable<JNode> buildSearch(String text, Set<SearchDialog.SearchOptions> options) {
+	public Flowable<JNode> buildSearch(String text, Set<SearchDialog.SearchOptions> options)
+			throws SearchSettings.InvalidSearchTermException {
 		boolean ignoreCase = options.contains(IGNORE_CASE);
 		boolean useRegex = options.contains(USE_REGEX);