is_symlink: correct logic for empty

Author: scivision

+stdlib/+dotnet/is_symlink.m

@@ -5,6 +5,11 @@
   file (1,1) string
 end
 
+if stdlib.strempty(file)
+  y = false;
+  return
+end
+
 try
   if stdlib.dotnet_api() >= 6
     y = ~isempty(System.IO.FileInfo(file).LinkTarget);

+stdlib/+java/is_symlink.m

@@ -1,10 +1,15 @@
-function ok = is_symlink(file)
+function y = is_symlink(file)
+
+if stdlib.strempty(file)
+  y = false;
+  return
+end
 
 try
-  ok = java.nio.file.Files.isSymbolicLink(javaAbsolutePath(file));
+  y = java.nio.file.Files.isSymbolicLink(javaAbsolutePath(file));
 catch e
   javaException(e)
-  ok = logical.empty;
+  y = logical.empty;
 end
 
 end

+stdlib/+python/is_symlink.m

@@ -1,5 +1,10 @@
 function y = is_symlink(file)
 
+if stdlib.strempty(file)
+  y = false;
+  return
+end
+
 try
   y = py.pathlib.Path(file).is_symlink();
 catch

+stdlib/+sys/is_symlink.m

@@ -1,4 +1,9 @@
-function [ok, cmd] = is_symlink(file)
+function [y, cmd] = is_symlink(file)
+
+if stdlib.strempty(file)
+  y = false;
+  return
+end
 
 if ispc()
   cmd = sprintf('fsutil reparsepoint query "%s"', file);
@@ -9,6 +14,6 @@
 end
 
 [s, ~] = system(cmd);
-ok = s == 0;
+y = s == 0;
 
 end