WIP: Fix issue with printing nullptr

src/Perlang.Interpreter/Compiler/PerlangCompiler.cs

@@ -250,7 +250,7 @@ private void RegisterGlobalClasses()
 
         if (process.ExitCode != 0)
         {
-            runtimeErrorHandler(new RuntimeError(null, $"Process exited with exit code {process.ExitCode}"));
+            runtimeErrorHandler(new RuntimeError(null, $"Process {executablePath} exited with exit code {process.ExitCode}"));
         }
 
         return executablePath;

src/Perlang.Tests.Integration/EvalException.cs

@@ -0,0 +1,12 @@
+#nullable enable
+using System;
+
+namespace Perlang.Tests.Integration;
+
+public class EvalException : Exception
+{
+    public EvalException(string message, Exception innerException)
+        : base(message, innerException)
+    {
+    }
+}

src/Perlang.Tests.Integration/EvalHelper.cs

@@ -267,6 +267,11 @@ internal static EvalResult<Exception> EvalWithResult(string source, params strin
                     // is known to not yet work.
                     throw new SkipException(e.Message);
                 }
+                catch (EvalException e)
+                {
+                    // For now, re-throw this as-is.
+                    throw;
+                }
 
                 // Return something else than `null` to make it reasonable for callers to distinguish that compiled mode
                 // (with no native "result") is being used, if needed.
@@ -379,22 +384,22 @@ private static void AssertFailParseErrorHandler(ParseError parseError)
 
         private static void AssertFailNameResolutionErrorHandler(NameResolutionError nameResolutionError)
         {
-            throw new Exception($"NameResolutionError occurred: {nameResolutionError.Message}", nameResolutionError);
+            throw new EvalException($"NameResolutionError occurred: {nameResolutionError.Message}", nameResolutionError);
         }
 
         private static void AssertFailRuntimeErrorHandler(RuntimeError runtimeError)
         {
-            throw new Exception($"RuntimeError occurred: {runtimeError.Message}", runtimeError);
+            throw new EvalException($"RuntimeError occurred: {runtimeError.Message}", runtimeError);
         }
 
         private static void AssertFailValidationErrorHandler(ValidationError validationError)
         {
-            throw new Exception($"ValidationError occurred: {validationError.Message}", validationError);
+            throw new EvalException($"ValidationError occurred: {validationError.Message}", validationError);
         }
 
         private static bool AssertFailCompilerWarningHandler(CompilerWarning compilerWarning)
         {
-            throw new Exception($"CompilerWarning occurred: {compilerWarning.Message}", compilerWarning);
+            throw new EvalException($"CompilerWarning occurred: {compilerWarning.Message}", compilerWarning);
         }
     }
 }

src/stdlib/src/print.cpp

@@ -10,9 +10,14 @@ namespace perlang
 {
     void print(const char* str)
     {
-        // For plain strings, there's no need to use the overhead which `printf` induces. `puts` can potentially be a
-        // tiny bit faster.
-        puts(str);
+        if (str == nullptr) {
+            puts("null");
+        }
+        else {
+            // For plain strings, there's no need to use the overhead which `printf` induces. `puts` can potentially be a
+            // tiny bit faster.
+            puts(str);
+        }
     }
 
     void print(bool b)