Throw exception instead of returning null if file can't be read.

src/helma/framework/repository/FileResource.java

@@ -54,12 +54,8 @@ public class FileResource extends AbstractResource {
         return baseName;
     }
 
-    public InputStream getInputStream() {
-        try {
+    public InputStream getInputStream() throws IOException {
         return new FileInputStream(file);
-        } catch (FileNotFoundException ex) {
-            return null;
-        }
     }
 
     public URL getUrl() {