Do not crash when a broken symlink is encountered

 "Broken symlink at {$relative_filepath}. Target missing at {$item->getLinkTarget()}."

features/distignore.feature

@@ -385,3 +385,23 @@ Feature: Generate a distribution archive of a project
       | targz  | tar.gz    | tar -zxvf | foo            |
       | zip    | zip       | unzip     | bar7           |
       | targz  | tar.gz    | tar -zxvf | bar8           |
+
+  Scenario: Does not crash when a broken symlink is encountered
+    # @see https://github.com/wp-cli/dist-archive-command/issues/86
+    Given an empty directory
+    And an empty foo/target-directory directory
+    And a foo/.distignore file:
+      """
+      """
+
+    When I run `ln -s {RUN_DIR}/foo/target-directory {RUN_DIR}/foo/symlink`
+    Then STDERR should be empty
+
+    When I run `rm -rf {RUN_DIR}/foo/target-directory`
+    Then STDERR should be empty
+
+    When I try `wp dist-archive foo`
+    Then STDERR should contain:
+      """
+      Error: Broken symlink at /symlink. Target missing at
+      """

src/Dist_Archive_Command.php

@@ -484,10 +484,18 @@ private function get_file_list( $source_dir_path, $excluded = false ) {
 		 */
 		foreach ( $iterator as $item ) {
 			$relative_filepath = str_replace( $source_dir_path, '', $item->getPathname() );
-			if ( $this->checker->isPathIgnored( $relative_filepath ) ) {
-				$excluded_files[] = $relative_filepath;
-			} else {
-				$included_files[] = $relative_filepath;
+			try {
+				if ( $this->checker->isPathIgnored( $relative_filepath ) ) {
+					$excluded_files[] = $relative_filepath;
+				} else {
+					$included_files[] = $relative_filepath;
+				}
+			} catch ( \Inmarelibero\GitIgnoreChecker\Exception\InvalidArgumentException $exception ) {
+				if ( $item->isLink() && ! file_exists( readlink( $item->getPathname() ) ) ) {
+					WP_CLI::error( "Broken symlink at {$relative_filepath}. Target missing at {$item->getLinkTarget()}." );
+				} else {
+					WP_CLI::error( $exception->getMessage() );
+				}
 			}
 		}