Handle exceptions in userdata functions gracefully, instead of crashing the whole stack down.

PorygonSharp/EvalValues/DelegateEvalValue.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Linq;
 using System.Runtime.InteropServices;
+using PorygonSharp.UserData;
 using PorygonSharp.Utilities;
 
 namespace PorygonSharp.EvalValues
@@ -32,8 +33,15 @@ namespace PorygonSharp.EvalValues
                 parameters[i] = Caster.Cast(val, parametersTypes[i]);
             }
 
+            try
+            {
                 var result = _delegate.DynamicInvoke(parameters);
-            return EvalValueCreator.CreateValue(result).GetPointer();
+                return new UserDataReturnValue(EvalValueCreator.CreateValue(result)).GetPointer();
+            }
+            catch (Exception e)
+            {
+                return new UserDataReturnValue(e.ToString()).GetPointer();
+            }
         }
     }
 }

PorygonSharp/EvalValues/EvalValue.cs

@@ -105,7 +105,7 @@ namespace PorygonSharp.EvalValues
             return Handle;
         }
 
-        public bool IsNumericValueFloat()
+        private bool IsNumericValueFloat()
         {
             return IsNumericValueFloat(Handle) == 1;
         }

PorygonSharp/UserData/UserDataFunctionField.cs

@@ -42,8 +42,15 @@ namespace PorygonSharp.UserData
                 }
 
                 var parentObj = GCHandle.FromIntPtr(parent).Target;
+                try
+                {
                     var result = method.Invoke(parentObj, evaluatedParameters);
-                return EvalValueCreator.CreateValue(result).GetPointer();
+                    return new UserDataReturnValue(EvalValueCreator.CreateValue(result)).GetPointer();
+                }
+                catch (Exception e)
+                {
+                    return new UserDataReturnValue(e.ToString()).GetPointer();
+                }
             };
         }
 

PorygonSharp/UserData/UserDataReturnValue.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Runtime.InteropServices;
+using PorygonSharp.EvalValues;
+
+namespace PorygonSharp.UserData
+{
+    internal class UserDataReturnValue
+    {
+        private readonly IntPtr _ptr;
+        public UserDataReturnValue(EvalValue value)
+        {
+            _ptr = ReturnValue(value.GetPointer());
+        }
+        
+        public UserDataReturnValue(string message)
+        {
+            _ptr = ErrorValue(message);
+        }
+        public static implicit operator UserDataReturnValue(EvalValue val)
+        {
+            return new UserDataReturnValue(val);
+        }
+
+        internal IntPtr GetPointer()
+        {
+            return _ptr;
+        }
+        
+        [DllImport("PorygonLang", EntryPoint = "ReturnValue", CallingConvention = CallingConvention.Cdecl)]
+        private static extern IntPtr ReturnValue(IntPtr value);
+        
+        [DllImport("PorygonLang", EntryPoint = "ErrorValue", CallingConvention = CallingConvention.Cdecl)]
+        private static extern IntPtr ErrorValue(string message);
+    }
+}

PorygonSharpTests/PorygonSharpTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>netcoreapp2.2</TargetFramework>
+        <TargetFramework>netcoreapp3.0</TargetFramework>
 
         <IsPackable>false</IsPackable>
     </PropertyGroup>