fix(gui): NPE if the autosave is enabled and project is initial (PR #565)

jadx-gui/src/main/java/jadx/gui/settings/JadxProject.java

@@ -91,6 +91,7 @@ public class JadxProject {
 	}
 
 	public void save() {
+		if (getProjectPath() != null) {
 			try (BufferedWriter writer = Files.newBufferedWriter(getProjectPath())) {
 				writer.write(GSON.toJson(this));
 				saved = true;
@@ -98,6 +99,7 @@ public class JadxProject {
 				LOG.error("Error saving project", e);
 			}
 		}
+	}
 
 	public static JadxProject from(Path path, JadxSettings settings) {
 		try {