Fix handling of symlinks extracted from zip files

Setting unix attributes was breaking the detection of symlinks by
Archive::Zip, so it was just writing out a file with the name of the
linked file in it.

Fix it by instead removing an existing file if it exists and not setting
permissions for symlinks. This allows Arhive::Zip to always create a
proper symlink. While at it, change the permissions for files to we
writable by the owner, so as to avoid any other permissions issues when
re-indexing an archive, which needs to replace existing files.

Finallky, don't abandon unzipping a file on error, but just move on to
the next file.

Changes

@@ -1,6 +1,8 @@
 Revision history for Perl extension PGXN::API
 
 0.20.2
+      - Fixed symlinks extracted from Zip files and permission errors when
+        re-indexing distributions.
 
 0.20.1  2024-02-15T22:18:14Z
       - Fixed a bug where a testing extension's version and abstract was not

lib/PGXN/API/Sync.pm

@@ -194,14 +194,20 @@ sub unzip {
     make_path $dist_dir unless -e $dist_dir && -d _;
 
     foreach my $member ($zip->members) {
-        # Make sure the file is readable by everyone
-        $member->unixFileAttributes( $member->isDirectory ? 0755 : 0444 );
         my $fn = catfile $dist_dir, split m{/} => $member->fileName;
         say "    $fn\n" if $self->verbose > 2;
+
+        if ($member->isSymbolicLink) {
+            # Delete exsting so Archive::Zip won't fail to create it.
+            warn "Cannot unlink $fn: $!\n" if -e $fn && !unlink $fn;
+        } else {
+            # Make sure the member is readable by everyone.
+            $member->unixFileAttributes( $member->isDirectory ? 0755 : 0644 );
+        }
+
         if ($member->extractToFileNamed($fn) != AZ_OK) {
-            warn "Error extracting $zip_path\n";
-            ## XXX clean up the mess here.
-            return;
+            warn "Error extracting $fn from $zip_path\n";
+            next;
         }
     }