Use the message of UnsupportedTypeException if it has one

* This is notably useful for conflicts with host interop like:
  ruby -e 'Java.type("java.util.concurrent.Executors").newFixedThreadPool(1).submit {}'
  -e:1:in `<main>': Multiple applicable overloads found for method name submit (candidates: [
     Method[public java.util.concurrent.Future java.util.concurrent.AbstractExecutorService.submit(java.util.concurrent.Callable)],
     Method[public java.util.concurrent.Future java.util.concurrent.AbstractExecutorService.submit(java.lang.Runnable)]],
     arguments: [RubyProc@3bfc6a5e<Proc> (RubyProc)]) (TypeError)

Author: eregon

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

@@ -698,9 +698,13 @@ public RubyException typeError(String message, Node currentNode, Throwable javaT
 
     @TruffleBoundary
     public RubyException typeErrorUnsupportedTypeException(UnsupportedTypeException exception, Node currentNode) {
-        RubyArray rubyArray = createArray(context, language, exception.getSuppliedValues());
-        String formattedValues = RubyGuards.getJavaString(DispatchNode.getUncached().call(rubyArray, "inspect"));
-        return typeError("unsupported type " + formattedValues, currentNode);
+        String message = exception.getMessage();
+        if (message == null) {
+            RubyArray rubyArray = createArray(context, language, exception.getSuppliedValues());
+            String formattedValues = RubyGuards.getJavaString(DispatchNode.getUncached().call(rubyArray, "inspect"));
+            message = "unsupported type " + formattedValues;
+        }
+        return typeError(message, currentNode);
     }
 
     // NameError