[fix] handle IllegalStateException in file:directory-list#2

fixes eXist-db#5028

The Java code of DirectoryList can throw an IllegalStateException
when a non-existent directory is supplied as its first argument.
This exception class is now handled in file:list#2.

Additionally, the raised error now has a proper code `file:DIRECTORY_NOT_FOUND`.

This will allow us in the future to add proper error codes to more
errors raised by this module.

extensions/modules/file/src/main/java/org/exist/xquery/modules/file/DirectoryList.java

@@ -24,7 +24,6 @@
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.Date;
 
 import org.apache.logging.log4j.LogManager;
@@ -34,11 +33,7 @@
 import org.exist.dom.QName;
 import org.exist.dom.memtree.MemTreeBuilder;
 import org.exist.util.FileUtils;
-import org.exist.xquery.BasicFunction;
-import org.exist.xquery.Cardinality;
-import org.exist.xquery.FunctionSignature;
-import org.exist.xquery.XPathException;
-import org.exist.xquery.XQueryContext;
+import org.exist.xquery.*;
 import org.exist.xquery.value.DateTimeValue;
 import org.exist.xquery.value.FunctionParameterSequenceType;
 import org.exist.xquery.value.FunctionReturnSequenceType;
@@ -47,9 +42,11 @@
 import org.exist.xquery.value.SequenceType;
 import org.exist.xquery.value.Type;
 
+import static org.exist.xquery.modules.file.FileErrorCode.DIRECTORY_NOT_FOUND;
+
 /**
  * eXist File Module Extension DirectoryList
- *
+ * <p>
  * Enumerate a list of files, including their size and modification time, found
  * in a specified directory, using a pattern
  *
@@ -121,7 +118,7 @@ public Sequence eval(final Sequence[] args, final Sequence contextSequence) thro
         builder.addAttribute(new QName("directory", null, null), baseDir.toString());
         try {
             final int patternsLen = patterns.getItemCount();
-            final String includes[] = new String[patternsLen];
+            final String[] includes = new String[patternsLen];
             for (int i = 0; i < patternsLen; i++) {
                 includes[i] = patterns.itemAt(0).getStringValue();
             }
@@ -172,8 +169,8 @@ public Sequence eval(final Sequence[] args, final Sequence contextSequence) thro
             builder.endElement();
 
             return (NodeValue) builder.getDocument().getDocumentElement();
-        } catch (final IOException e) {
-            throw new XPathException(this, e.getMessage());
+        } catch (final IOException | IllegalStateException e) {
+            throw new XPathException(this, DIRECTORY_NOT_FOUND, e.getMessage());
         } finally {
             context.popDocumentContext();
         }

extensions/modules/file/src/main/java/org/exist/xquery/modules/file/FileErrorCode.java

@@ -0,0 +1,12 @@
+package org.exist.xquery.modules.file;
+
+import org.exist.dom.QName;
+import org.exist.xquery.ErrorCodes;
+
+class FileErrorCode extends ErrorCodes.ErrorCode {
+    public static final ErrorCodes.ErrorCode DIRECTORY_NOT_FOUND = new FileErrorCode("DIRECTORY_NOT_FOUND", "Index cannot be applied to the given expression.");
+
+    FileErrorCode(String code, String description) {
+        super(new QName(code, FileModule.NAMESPACE_URI, FileModule.PREFIX), description);
+    }
+}

extensions/modules/file/src/test/xquery/modules/file/directory-list.xqm

@@ -0,0 +1,48 @@
+(:
+ : eXist-db Open Source Native XML Database
+ : Copyright (C) 2001 The eXist-db Authors
+ :
+ : [email protected]
+ : http://www.exist-db.org
+ :
+ : This library is free software; you can redistribute it and/or
+ : modify it under the terms of the GNU Lesser General Public
+ : License as published by the Free Software Foundation; either
+ : version 2.1 of the License, or (at your option) any later version.
+ :
+ : This library is distributed in the hope that it will be useful,
+ : but WITHOUT ANY WARRANTY; without even the implied warranty of
+ : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ : Lesser General Public License for more details.
+ :
+ : You should have received a copy of the GNU Lesser General Public
+ : License along with this library; if not, write to the Free Software
+ : Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ :)
+xquery version "3.1";
+
+module namespace dirlist="http://exist-db.org/testsuite/modules/file/dirlist";
+
+
+import module namespace file="http://exist-db.org/xquery/file";
+import module namespace util="http://exist-db.org/xquery/util";
+import module namespace helper="http://exist-db.org/xquery/test/util/helper" at "resource:util/helper.xqm";
+
+declare namespace test="http://exist-db.org/xquery/xqsuite";
+
+
+declare
+    %test:assertError("file:DIRECTORY_NOT_FOUND")
+function dirlist:non-existent-error-code() {
+    file:directory-list("/non/existent", ())
+};
+
+declare
+    %test:assertXPath("contains($result,'basedir /non/existent does not exist.')")
+function dirlist:non-existent-error-description() {
+    try {
+        file:directory-list("/non/existent", ())
+    } catch file:DIRECTORY_NOT_FOUND {
+        $err:description
+    }
+};