add patch files for 106_files.zig

exercises/106_files.zig

@@ -35,8 +35,8 @@ pub fn main() !void {
         // by doing nothing
         //
         // we want to catch error.PathAlreadyExists and do nothing
-        ??? => {
-            ???
+        error.PathAlreadyExists => {
+            return;
         },
         // if is any other unexpected error we just propagate it through
         else => return e,
@@ -46,7 +46,7 @@ pub fn main() !void {
     // wait a minute
     // opening a directory might fail!
     // what should we do here?
-    const output_dir: std.fs.Dir = cwd.openDir("output", .{});
+    const output_dir: std.fs.Dir = try cwd.openDir("output", .{});
 
     // we try to open the file `zigling.txt`,
     // and propagate the error up if there are any errors
@@ -56,7 +56,7 @@ pub fn main() !void {
     // but here we are not yet done writing to the file
     // if only there are a keyword in zig that
     // allow you "defer" code execute to the end of scope...
-    file.close();
+    defer file.close();
 
     // !you are not allow to switch this two lines to before file closing line!
     const byte_written = try file.write("It's zigling time!");