Refactor RubyException - remove incorrect assert in a constructor that ensures a message has a proper type

Author: andrykonchin

src/main/java/org/truffleruby/core/exception/RubyException.java

@@ -26,9 +26,6 @@
 import org.truffleruby.core.array.RubyArray;
 import org.truffleruby.core.klass.RubyClass;
 import org.truffleruby.core.proc.RubyProc;
-import org.truffleruby.core.string.RubyString;
-import org.truffleruby.core.string.ImmutableRubyString;
-import org.truffleruby.language.Nil;
 import org.truffleruby.language.RubyDynamicObject;
 import org.truffleruby.language.backtrace.Backtrace;
 import org.truffleruby.language.objects.ObjectGraph;
@@ -42,6 +39,7 @@
 @ExportLibrary(InteropLibrary.class)
 public class RubyException extends RubyDynamicObject implements ObjectGraphNode {
 
+    /** message may be an instance of any class */
     public Object message;
     public Backtrace backtrace;
     public Object cause;
@@ -55,9 +53,6 @@ public class RubyException extends RubyDynamicObject implements ObjectGraphNode
 
     public RubyException(RubyClass rubyClass, Shape shape, Object message, Backtrace backtrace, Object cause) {
         super(rubyClass, shape);
-        // TODO (eregon, 9 Aug 2020): it should probably be null or RubyString, not nil, and the field can then be typed
-        assert message == null || message == Nil.INSTANCE || message instanceof RubyString ||
-                message instanceof ImmutableRubyString;
         assert cause != null;
         this.message = message;
         this.backtrace = backtrace;