feat: add exception catch to code generator.

Author: SanftMonster

tools/Tensorflow.CodeGen/FunctionGenerator.cs

@@ -83,6 +83,10 @@ public void AppendFunction(OpDef op, StringBuilder sb)
 
                 sb.AppendLine("}"); // try
 
+                sb.Append("catch(NotOkStatusException ex)\n{\n");
+                sb.AppendLine("throw ex;");
+                sb.AppendLine("}"); // catch
+
                 sb.Append("catch(Exception)\n{\n");
                 sb.AppendLine("}"); // catch