#343 Improve error handling for missing srcDir

Check if the source directory exists or if any other IOException occurs
while retrieving source documents. Exit if none can be found.

Author: ascheman

htmlSanityCheck-cli/src/main/groovy/org/aim42/htmlsanitycheck/cli/HscCommand.groovy

@@ -105,7 +105,6 @@ class HscCommand implements Runnable {
     File[] srcDocs
 
     static void main(String[] args) {
-
         HscRunner hscRunner = new HscRunner()
         HscCommand hscCommand = new HscCommand(hscRunner)
         CommandLine cmd = new CommandLine(hscCommand)
@@ -114,13 +113,24 @@ class HscCommand implements Runnable {
         cmd.execute(args)
     }
 
-    private List<File> findFiles() throws IOException {
-        Files.walk(Paths.get(srcDir.getPath()))
-                .filter(Files::isRegularFile)
-                .filter({ path ->
-                    suffixes.any { suffix -> path.toString().endsWith(".${suffix}") }
-                })
-                .collect { Path path -> path.toFile() }
+    private List<File> findFiles() {
+        var srcPath = Paths.get(srcDir.getPath())
+        if (!Files.exists(srcPath)) {
+            logger.severe("Source directory or file '${srcDir}' does not exist")
+            System.exit(2)
+        }
+        try {
+            return Files.walk(srcPath)
+                    .filter(Files::isRegularFile)
+                    .filter({ path ->
+                        suffixes.any { suffix -> path.toString().endsWith(".${suffix}") }
+                    })
+                    .collect { Path path -> path.toFile() }
+        } catch (IOException e) {
+            logger.severe("Cannot check HTML files in '${srcDir}': '${e}'")
+            System.exit(2)
+        }
+        return null
     }
 
     static class HscRunner {